I think they'd find pretty similar stuff to what they find on Facebook. With an extra anonymous/paranoid twist
And that we're the greatest people in the world, super-smart, super-creative, but with
way too much time on our hands.
Or in my case, not really too much time on my hands, because there's plenty I could be doing instead, I just don't always use the time I have wisely

EDIT: seriously, I think a lot of the same criteria could apply here, just with a little adaptation. For instance, people who start a lot of threads
but rarely bother to read other people's thoughts probably tend towards narcissism. People who use U2U a lot probably have made pretty significant
relationships here. People who only frequent one or two specific forums might be using it more as a "career-networking" or "hobby-networking"
site rather than as a social site.
Avatars would be a little harder, because whereas on Facebook most people use their own picture, that's relatively uncommon here. I had to laugh,
though, about the contrast between people who used glamorous, self-promotional shots vs. people who use snapshots: it fits awful well with my own
collection of Facebook friends
[edit on 9/24/08 by americandingbat]