This is cool. A CalTech student named Adam D'Angelo was thinking about Instant Messenger buddy lists, and realized they formed a massive network. If I have person A on my buddy list, and person A has person Q on their list -- then I am effectively linked to person Q.

So D'Angelo created BuddyZoo -- a tool that lets you upload your buddy lists and then generate a visual map showing how you're linked to the world. For even more fun, he's crunched data on buddy lists from college students -- and determined that CalTech has the most popular students on the planet, heh.