Traditional desktop PCs need at least one monitor, and many people extol the virtues of working with two or more, even with a laptop on a desk. For many years the VGA connector reigned supreme as the standard way to connect monitors to PCs, but the transition from analog to digital video connections has created a hodgepodge of standards in VGA's wake, starting with a standard called DVI (Digital Video Interleave).
Since then, most PCs and video cards have opted for HDMI (High Definition Multimedia Interface), DisplayPort, or mini-DisplayPort connectors (the latter adopted by Apple on most Macs). HDMI ports may be nearly ubiquitous on today's HDTVs, but for the 12 months ending April 2012, just 33 percent of monitors sold had at least one HDMI port according to NPD's Retail Tracking Service.
But there's one connector that virtually every PC has that not many people know can be used to send video to an external monitor -- the USB port. USB is normally used for connecting products such as hard drives, keyboards, and printers. However, with the right monitor and drivers from a company called DisplayLink, Macs and PCs can use USB connectors to support external displays. In fact, DisplayLink supports connecting up to six monitors for PCs with that many USB ports, although productivity generally tends to decline trying to track things down floating among so many oceans of pixels.
DisplayLink can work with monitors that have other, more popular connectors, such as HDMI and DVI, even across a wireless connection (using the rarely used wireless USB standard), but connecting with other monitors usually requires a bulky conversion box. And, of course, those monitors need to be plugged in. DisplayLink really shines when it is used with a monitor that supports it natively. Just load the drivers, connect to the monitor via a USB cable and, after some disconcerting screen theatrics, you can either mirror or extend your desktop just as you would with any other external monitor.
Some of the first DisplayLink monitors were 7" to 10", large enough to hold perhaps an instant messaging window or some Windows 7 gadgets, but relatively dim. Recently, though, DisplayLink monitors have gotten much larger and more practical for real work, with monitor maker AOC offering 16" and even 22" DisplayLink monitors.
They might not be quite as bright as an AC-powered display, but they are bright enough for most computing tasks. And since they are slim and powered by the same single USB cable used to provide the video, they are great traveling companions for when you need to get extra work done on the road without constantly flipping back and forth among windows.
Perhaps because they are intended to be used infrequently or to help keep costs down, though, these displays tend to not have power switches. The only way to turn them off is to unplug them.