I'm mostly on facebook and try to check dp everyday, other than that i have an account on twiiter, but i rarely use it
Facebook for close friends, using it everyday. Twitter to my online public and rage sometimes with TT's, I use it 3-4 times a week, currently using linkedin in a very serious way. I use deviantart sometimes (its not exactly social but works fine for some purposes). I have never used myspace and I don't plan to use it.
I use Facebook most of the time and apart from Facebook, i have resistered in twitter, Linkedin, myspace,digg and delicious..
I am active in Facebook, Twitter, YouTube and some popular forums like warriorforum, webmastertalk, digitalpoint forum, etc. It takes time, but enjoy to use those sites.
Used to love StumbleUpon so much few years ago until it sent like Zero traffic to my blog somehow nowadays. Active more on Facebook and sometimes Twitter
I use Facebook mostly because all my friends are there and they don’t have other accounts in other social networks