Cool! I just discovered Friend.ly, a Facebook application that analyzes yours friends' demographic information and outputs basic statistics.
Thought I'd post my friend stats here so that you could all psychoanalyze me!
Most common name: Kevin (11 friends)
Most common zodiac sign: Libra (83 friends)
Longest name: Maximillian-Conroy Hencke
Shortest name: Yi Li
Female/Male: 50% / 50%
Single/Taken: 39% / 61%
Youngest friend: 17 years old
Oldest friend: 105 years old
Average age: 23 years old
If you're interested, go try it yourself at http://friend.ly!
Note: You can click "Don't Allow" for both prompt boxes and it will still calculate the statistics. Plus, you don't even have to publish the output to your Facebook news feed!