10 Fascinating Facebook Facts

July 24, 2010— -- Facebook's astronomic rise, staggeringly large user-base, and world's youngest self-made billionaire CEO make it one of the most fascinating companies around today.

While everyone knows the basics about the service's Harvard dorm room origins, we've delved a little deeper to find out more interesting snippets of info.

Here are 10 facts you might not know about Facebook, so read on and let us know your favorites in the comments box below.

1. Al Pacino's Face Was on the Original Facebook Homepage

Prior to a major homepage redesign back in 2007, Facebook's front page used to feature a man's face partly obscured behind a cloud of binary code.

Dubbed the "Facebook guy," it was not known who the mystery man was — until recently. David Kirkpatrick has revealed in his book The Facebook Effect that the image is a manipulated photo of Al Pacino created by a friend and classmate of Mark Zuckerberg.

2. One Early Facebook Function Was a File Sharing Service

You won't find this in the official Facebook timeline, but one of Facebook's early add-ons was a peer-to-peer, or more technically friend-to-friend, file sharing service called Wirehog, developed alongside Facebook by Mark Zuckerberg and three others.

It launched in 2004 and is reported to have been planned as an integral FB feature. In 2005 Facebook was actively promoting the service and Zuckerberg told The Harvard Crimson "I think Wirehog will probably spread in the same way that thefacebook did."

However, likely due to piracy concerns, Wirehog was axed in 2006 before Facebook got really big, although its photo-sharing functionality lives on in spirit.

3. The First "Work Networks" Included Apple and Microsoft

Many of you may know about Facebook's initial staggered rollout, where they started with Ivy League colleges before encompassing other educational institutions. But do you know who Facebook first went corporate with in terms of official work places?

In May 2006, Apple and Microsoft were among the first, as was Intel, EA and Amazon. Others in the first round also included Accenture, Gap, Intuit, Pepsi, PricewaterhouseCoopers and the non-profit organization Teach for America. It wasn't until September 2006 that everyone, regardless of school or company affiliation, could join Facebook — and just over a year later the site hit 50 million active users.