I've been playing around with a number of so-called Social Software/Social Networking sites for about six months.
I'm currently on Ryze with supposedly 13 'Friends' and 414 in 'Network', and Tribe.net with 20 'Friends' and 17,677 in my 'Network'. I've registered for a few others, but wasn't able to get them going much beyond registering. However, I have not registered for Friendster yet, as it was originally a dating site but I understand now that it is more then that.
These Social Networking sites have been interesting, but so far none have been a really useful to me.
I've identified a few problems:
All that I've joined feel just a bit off -- but yet I still believe there is something useful in Social Software to learn that I just have to puzzle out.