Top 50 Tech Visionaries

— -- Courtesy of David WeeklyA jack-of-all-tech-trades, Alan Kay lays claim to at least two watershed innovations, starting with HP's original Dynabook, one of the first usable mobile laptop computers. Kay ideal was to design a laptop that weighed no more than 2 pounds. We still aren't there yet, but Kay's contributions to software--which include shepherding the idea of object-oriented programming and the notion of multiple, overlapping windows in a GUI--rank as essential milestones in computing.

20. Marc Andreessen

Courtesy of Duncan DavidsonThe Mosaic Web browser devised by Marc Andreessen may seem quaint now, but bits and pieces of Mosaic code remain standard software components of most of today's commercial browsers. It's a safe bet that many of Andreessen's other creations will leave similar legacies: Netscape, the company he founded, set off the tech stock craze of the 1990s, and his Ning Web site continues to grow in popularity as an outlet where anyone can build a topic-oriented social network. He even finds time to blog regularly about all this stuff.

21. Linus Torvalds

Courtesy of Martin Streicher, Linuxmag.comGiven the exorbitant cost of most Apple computers, Linus Torvalds is the godfather of what may be the last, best hope for an affordable alternative to Windows. The Linux operating system has been in continuous development since Torvalds conceived it in 1991, and has experienced steady gains in popular acceptance every year. And a long last, Linux is making the jump from server rooms to large numbers of desktop PCs, most visibly in low-cost laptops like the Asus Eee PC. The OS now has a market share in excess of 2 percent on the desktop.

22. Chuck Thacker

Courtesy of MicrosoftChuck Thacker has had his hands in a surprisingly wide array of tech projects, from the development of ethernet to the first laser printers. His most enduring legacy, however, involves a product that never reached market: The fabled Xerox Alto. The Alto, which Thacker designed, was the first computer with a GUI (and a mouse); as the story goes, it directly inspired Apple to build the Macintosh after Steve Jobs paid a friendly visit to Xerox. Thacker now works for Microsoft.

23. Bob Metcalfe

Courtesy of Wikimedia CommonsMoore's Law may be better known, but the law formulated by Bob Metcalfe has wider general application. Posited around 1980, Metcalfe's Law conjectured that the value of a telecommunications network is equal to the square of the number of nodes on the network. In other words, even a small increase in the size of a network makes it worth far more because of the enlarged number of new connections that each user can make. Metcalfe's invention of ethernet and his founding of 3Com are essential tech milestones as well, but his eponymous law--now in use to quantify value in the Facebook/MySpace milieu--will be around long after wired networking has passed on.

24. Vic Hayes

Courtesy of IEEEWi-Fi has long been one of technology's messiest standards--and without Vic Hayes, it might never have come together at all. In the Hayes-less universe we might be left to wallow in a morass similar to the a Blu-ray vs. HD-DVD swamp with multiple incompatible wireless standards. In 1990, Hayes formed the Wireless LAN working group and rallied some 130 companies to work together to develop open standards. The result: 802.11, and the cutting of a very firmly attached cord. Hayes continues to be actively involved in Wi-Fi development today.

25. Dan Bricklin and Bob Frankston

Courtesy of Dan BricklinAccounting departments around the world would be lost without the work of Dan Bricklin (left) and Bob Frankston, who worked together in 1979 to develop VisiCalc, the world's first spreadsheet and arguably the first "killer app" written for a personal computer. The 27KB program can run on PCs today, and its simplicity is a big reason why early PCs sold in droves, especially to business customers. But never mind the bean-counters: You probably owe a lot to VisiCalc yourself. After all, if it weren't for Bricklin and Frankston, you might not be getting your paycheck regularly.

26. Grace Murray Hopper

Courtesy of Naval Historical CenterThat's Admiral Hopper, bud. Naval officer "Amazing" Grace Hopper was a computing pioneer who cut her teeth in the calculator era. Later she worked on the team that developed the UNIVAC, the world's first commercial computer, and wrote the compiler software for it (the first such software ever developed). Hopper was instrumental again in the development of the COBOL and FORTRAN programming languages, and she remained a major figure on the technology scene until her death in 1992. Even our language owes a debt to Hopper: She popularized (and possibly coined) the term "bug" after a moth was found in a computer relay during her years at Harvard.

Jeff Hawkins (#27) to Karlheinz Brandenburg and James D. Johnston (#34)

27. Jeff Hawkins

Courtesy of Ed SchipulPortable computing was shaped in large part by Jeff Hawkins, who invented the acclaimed PalmPilot, and then followed that up by spearheading development of the Treo six years later. Both Palm and Treo became household names, though Palm as a company has suffered numerous setbacks in recent years. Hawkins is now working on a startup called Numenta with his longtime partner Donna Dubinsky, focusing on the subjects of machine learning and neuroscience, which Hawkins has long had a deep interest in.

28. Fujio Masuoka

Courtesy of Unisantis ElectronicsIf anything is positioned to challenge the dominance of Al Shugart's hard drive (see #33 below), it's Flash memory--an invention of Fujio Masuoka. Masuoka developed solid-state storage during his tenure at Toshiba (Masuoka says that the company initially tried to demote him after he came up with the technology). The technology is now seen as a possible way around the fragility of hard drives, as capacity ramps up and prices fall. For smaller gadgets, Flash has become essential...or would you prefer to be saving your digital pictures on floppy disks still?

29. Jonathan Ive

Courtesy of AppleAside from its showman/CEO Steve Jobs, Apple tends to keep its employees out of the limelight, but Apple VP and design guru Jonathan Ive has broken that mold. That's appropriate, since he broke another mold too, killing off the beige boxes and bricklike pocket gizmos that had become standard-issue in the tech industry. Ive's designs for the original iMac and for the iPod got people thinking about tech products as fashion accessories and decorative items instead of as impersonal and purely utilitarian objects.

30. Jeff Bezos

Courtesy of Amazon.comLong scorned by Wall Street, Amazon.com--the creation of Jeff Bezos--is today the one Internet service that many people can't live without. But Bezos hasn't stopped at hawking Harry Potter on the Web. His company has also become one of the leading providers of Web services, online storage, and by-the-hour CPU rentals, as Bezos pushes Amazon toward becoming a platform that anyone can use to sell anything that Amazon itself doesn't.

31. Meg Whitman

Courtesy of eBayA longtime Hasbro marketing executive, Meg Whitman went from the child's toy box to the grown-up's as CEO of eBay. Whitman joined the online auction site in its infancy and over the course of a ten-year run shepherded it into one of the most successful businesses on the Web. (She retired in March of this year.) Aside from squabbles over policy changes and the baffling purchase of Skype, eBay's run has encountered few speed bumps. That success, some say, might lead her to run for governor of California in 2010, but Whitman denies harboring any such ambitions.

32. Bill Joy

Courtesy of Wikimedia CommonsA legend in tech circles, Bill Joy was chief scientist for Sun Microsystems for over 20 years, where he oversaw numerous critical technology advances, the most important of which was the development of Java--the first major programming language designed for use on the Web. Still, Joy's greatest achievement is probably an academic project he worked on at Berkeley: The development of Berkeley Software Distribution (BSD), a major flavor of Unix; even Mac OS X uses BSD as its basis. Today Joy spends his days worrying about the evils of technology, such as bad robots and Grey Goo (a scenario where renegade nanomachines run amok and destroy the world).

33. Al Shugart

Courtesy of ComputerworldYou're probably using a product conceived by Al Shugart right now without even knowing it. Shugart's company, Shugart Technology, switched to the more exotic-sounding name Seagate Technology soon after opening for business. At Seagate, Shugart developed technology that he had tinkered with during a stint at IBM (where he led the team that invented the floppy disk) into the hard drive for the mass market. The colorful Shugart ran Seagate for nearly 20 years before redefining himself as a sort of venture capitalist/promoter, a role that made him a staple at big tech shows like Comdex. Shugart died in 2006.

34. Karlheinz Brandenburg and James D. Johnston

Who says grad school is all impractical theory? At Friedrich-Alexander University, Karlheinz Brandenburg used his dissertation to work out a way of compressing digital audio files to radically smaller size without greatly deminishing their quality. We know the result now as MP3 coding. At AT&T Labs, American engineer James D. Johnston (left) improved on Brandenburg's work by introducing "perceptual coding," which strips out inaudible parts of an audio signal to compress the file further. Johnston's contribution, too, has become a standard feature of most audio compression schemes.

Ann Winblad (#35) to Alan Emtage with Bill Heelan and Mike Parker (#42)

35. Ann Winblad

Courtesy of MicrosoftHalf of the well-known Hummer Winblad Venture Partners investment group, Ann Winblad was a key figure in the Web 1.0 boom, investing in such proto-companies as Napster, Gazoontite, Liquid Audio, and Pets.com. Despite some ill-fated investments, Hummer Winblad picked enough winners to remain a lead investor in dozens of tech companies, primarily back-end enterprises. And lest you think that Winblad is merely a stuffed shirt, consider this: She began her career as a computer programmer in the 1970s and achieved indisputable nerd cred by having dated Bill Gates.

36. Charles Simonyi

Courtesy of NASACharles Simonyi (plus a little Gatesian muscle, natch) is the reason you use Word and Excel instead of WordPerfect and Quattro Pro. As head of Microsoft's application development group, Simonyi oversaw development of both Word and Excel back in the MS-DOS days and superintended the app suite for more than 20 years. The programs are now as close to ubiquitous as Windows itself (perhaps even closer, since Office is the standard app suite for the Mac as well). Fun facts to know and tell: Simonyi was the second Hungarian in space in space and is Martha Stewart's boyfriend.

37. Thomas Penfield Jackson

Courtesy of Jackson & CampbellFew people would have imagined that it a 62-year-old man unaffiliated with the company would have the most profound effect on Microsoft in years. But in 1999 U.S. District Court Judge Thomas Penfield Jackson shook the tech world to its foundations when he handed down a landmark ruling declaring Microsoft to be an abusive monopoly and ordering it split into two companies. Though appellate courts eventually overturned many of Jackson's rulings, Microsoft has been on the defensive against antitrust actions here and abroad ever since, and all tech companies looking to merge have had to tread more cautiously in Jackson's wake.

38.  Jerry Yang and David Filo

This unassuming twosome got their start in 1994 while still at Stanford, with a truly humble idea: Populate a directory with cool places that they had found on the then-infant World Wide Web. Yahoo was born on a lark but Jerry Yang (left) and David Filo helped it become one of the Web's top destinations: Today it is the home page for millions of people seeking the easiest entry point into the Internet. After an unfruitful turn with Hollywood insider Terry Semel at the helm, Yang retook the reins as CEO in June 2007. Yahoo is now coping with separate forays for control of the company by Microsoft and by Carl Icahn. (Full disclosure: The author writes a blog for Yahoo Tech.)

39. Peter Norton

A Buddhist monk before becoming invovled in the tech world, Peter Norton has been a major figure in the computer industry for three decades, having made his mark early in the DOS era with Norton Utilities, the first major data recovery tool for the PC. Norton went on to produce a gaggle of related utilities for the PC and write a series of essential technical manuals before selling his company to Symantec in 1990. Symantec still uses his name on its utility apps.

40. Phil Zimmermann

Courtesy of Wikimedia CommonsPhil Zimmermann fought the law so you don't have to. His Pretty Good Privacy (PGP) application, the first mainstream encryption software, published in 1991, made Zimmermann a pariah in the eyes of the U.S. government. The feds spent three years investigating the possibility that Zimmermann had violated rules forbidding the export of cryptographic tools. The case was ultimately dropped, however, paving the way for everyday people to protect the material on their hard drives and in their e-mail with the same encryption standards that the government itself uses.

41. Jon Postel

Courtesy of Irene Fertik, USC News Service. Copyright 1994How do you move from one IP address to another? Easily, thanks to Jon Postel, the so-called Father of DNS--the system that translates 70.42.185.10 into http://www.pcworld.com/. Postel also did substantial work on the TCP/IP and SMTP protocols, authoring some 200 Internet spec documents overall. But Postel didn't just envision the DNS system; he ran it himself for years as founding head of the Internet Assigned Numbers Authority (a position that led him into a memorable conflict with President Bill Clinton's science advisor when he tried to move control of DNS from Network Solutions to IANA). Postel died in 1998.

42. Alan Emtage with Bill Heelan and Mike Parker

Courtesy of Michael RhodesBefore Google--before the Web even--people had to find a way to locate files and programs hiding out on FTP servers around the world. The answer: Archie (a derivative of "archive"), a 1990 application devised by McGill University student Alan Emtage, who was assisted by Bill Heelan and Mike Parker. In its original incarnation, Archie contacted far-off FTP servers regularly and kept a local list of the files they contained, for easy indexing. That may sound like simple stuff by today's standards, but it inspired everything about the way we currently work with search, from the Web to the desktop.

Trip Hawkins (#43) to Udi Manber (#50)

43. Trip Hawkins

Courtesy of Digital ChocolateElectronic Arts is one of the few pure software companies that continues to be important 25 years after its founding--and it wouldn't have existed at all if not for gaming pioneer Trip Hawkins, a Harvard and Stanford grad and Apple alumnus who in 1982 saw the future in consoles and computer-based games. Hawkins's foray into hardware--he left EA to launch the 3DO in 1991--met with considerably less success, but his first baby continues to thrive. Just ask John Madden.

44. Arianna Huffington 

Courtesy of Huffington PostPolitical insider Arianna Huffington has had a major influence on technology, but one that has been felt only recently. She spent her early career inside the Washington, D.C., Beltway as a columnist, author, pundit, and TV show writer, far from the geek wiring of Silicon Valley. But in 2005 she launched a little online project called The Huffington Post, which rapidly grew into one of the Web's most powerful political voices. More than anything, the HuffPo has proven the power of the blog by attracting celebrity writers ranging from John Kerry to Jamie Lee Curtis, all eager to have their message heard through Huffington's medium.

45. Susan Kare

Courtesy of Susan KareAnother Macintosh 1.0 innovator, Susan Kare worked behind the scenes, but came up with essential innovations. Her earliest achievement was designing the typefaces--and  some of the, er, iconic icons--that shipped with the Macintosh. The "Happy Mac" remains one of computing's most visible expressions of things working well. Today Kare works as an independent designer: She designed the cards for Windows' ubiquitous Solitaire game and now designs Facebook's "Gifts" feature.

46. Sir Arthur C. Clarke

Courtesy of Scott ChaseSure, give Arthur C. Clarke credit for inspiring the minds of thousands of technology pioneers. But Clarke didn't just write seminal works of science fiction (including 2001: A Space Odyssey); he also conceived of geostationary communications satellites (satellites that orbit the earth at a speed proportional to the earth's rotation, so that the satellite always remains positioned above the same geographical point). Satellites with such orbits, sometimes termed the "Clarke satellite orbit," are essential to the telecommunications infrastructure, to GPS, and to numerous other technologies. Clarke died in March 2008 at age 90.

47. Herbie Hancock

Courtesy of Wikimedia CommonsWhen Herbie Hancock released his single, "Rockit" (from the album "Future Shock") in 1983, few listeners knew what to make of it. But everyone was struck by its unique sound--it was perhaps the first mainstream offering to use scratching. Though Hancock was by no means the first person to make heavy use of synthesizers, drum machines, and other computer-based musical equipment, few musicians relied so heavily on such gear and reached such a wide audience. "Rockit," with its innovative music video, is now considered a turning point in the electronic music-making scene, where Hancock is revered as an elder statesman.

48. William Gibson

Courtesy of Fred ArmitageThe king of cyberpunk, William Gibson, has dreamed up all manner of high-minded techno wizardry, some of which has actually started to come true. His early stories introduced the term "cyberspace" and the visualization concepts behind it, which in turn prompted people to start thinking about networks in a way that transcended text and a command line. We may not be plugging chips directly into our brains yet, but Gibson's fiction-based prophecies have a strange way of panning out.

49. Gary Kildall

Courtesy of Ipopisp.comCalled "The Man Who Could Have Been Bill Gates" by BusinessWeek, Gary Kildall was the guy Gates beat out in the bidding to supply IBM with the operating system for the original PC. According to legend, Kildall blew off the meeting with IBM to "go flying," though Kildall denied that rumor, posthumously, in his unpublished memoirs. Controversy aside, Kildall made significant contributions to the tech business--especially as the head of Digital Research, which created the seminal pre-DOS operating system CP/M, and (later) as a host of the classic Public TV program, Computer Chronicles. Kildall died in 1994.

50. Udi Manber

Courtesy of GoogleIf there is a search engine anywhere that doesn't have the the thumbprint of Udi Manber on it, we don't know about it. From Yahoo to Amazon's A9 to Google, Manber has been one of the search business's greatest contributers. But Manber's work goes back even farther than that, to AltaVista. He was a key member of the design team on what many feel was the best engine running until Google came along.

Christopher Null writes regularly for PC World and blogs about technology daily at tech.yahoo.com.