I'm personally addicted to some of the games over there: Scramble, Pathwords, GeoChallenge, Who Has the Biggest Brain, etc. Most especially PACK RAT!
And, this may sound ridiculous, but I have some of the FUNNIEST back-and-forths with my 17 year old on her wall!
I was late to the social networking thing, only opened a Facebook account a couple months ago on my 45th birthday. And I didn't really get it at first, what one was supposed to actually do.
Now I have about 40 friends and I'm forever chatting with people, playing word games, etc.