This weekend I played a bit with Friendster.com, the friend-of-a-friend social network site. I've been trying to see how extensive the network is so I've stretched things a bit and sent Friendster's preschoolish "Will you be my friend?" message to some net acquaintances who probably wouldn't consider me their friend friend.
With 15 friends and "friends" responding, I've pushed my "personal network" up to 28,000 people and climbing. Pretty amazing, especially since it seems that Friendster defines the "personal network" at a maximum of four degrees of separation. I wish Friendster offered a geek's-eye-view with statistics and such. Where are the key nodes in my personal network without which it would be much smaller? Where are the biggest redundancies? How does this compare with the size of other "personal networks" in the system? How is my "personal network" distributed geographically? I'm sure I don't even know the most interesting questions to ask -- I'm kind of fuzzy on my Malcolm Gladwell and my copy of Albert-László Barabási's Linked is still on my to-be-read shelf. Friendster could be a nice little laboratory in which to explore some of those ideas, given the right tools with which to probe one's network.
Update. What do you know, no sooner do I post this than my random RSS bot in the sidebar spits out an article on Friendster from the Village Voice: Six Degrees of Sexual Frustration. Cute. The article is short on facts but does say that Friendster reached 300,000 members in May (late May or early May? In Internet time it makes a big difference). So my "personal network" is in the ballpark of 10% of the total Friendster network. I don't know whether that supports my hunch that pretty soon everyone in Friendster will share one enormous "personal network" or not.