After reading an earlier thread on this message board about the Farmville game, I had to check it out. I created an account under a fake name using fictitious details, so there is no real personal information about me there. Then I tried out some of the games.
I play Frontierville regularly, and all my "friends" are fellow Frontierville players.
Of course I also looked up all kinds of people I've been out of touch with for years, so I've gotten to see what former classmates are up to now, and that's been fun.
I haven't contacted anyone via FB, though, and I don't plan to. I suppose if I ever want to, I can create a real account for that.