This site and LiveJournal excepted, (online) social networking - on any of the trendy sites, anyway - is unimportant to me.
I started a Stalkbook account a while back to see what the fuss was about. Whatever it is that so fascinates people completely passed me by. What put me off completely was Stalkbook's abysmal attitude to people's privacy. I had all my information set to private; when I logged into the place several months later I found that everything
I'd set to private had been re-set to public. Since I didn't do it, Stalkbook must have. That says it all about their views on people's online privacy and that was it so far as my use of the place goes. I don't intend to ever log in there again.
Twitface doesn't do anything for me, either, and I never bothered with any of the other options. As ever, to each their own.