I got dragged kicking and screaming onto Facebook by some friends, and I check in every now and again - well, I pop in once a day to see if I have messages (I rarely do) and have disabled most of the annoying things like pokes and random gifts and gardens and stuff. I don’t really like posting anything personal on there because it strikes me that I can’t be sure who sees me, even if they’re not my friends.
I have a vague recollection of signing up for a Myspace account - I probably have a profile on there somewhere, but I never went back to it after the first day, so it doesn’t count and I didn’t vote for it on the poll. I’ve never used any of the other options.