Social Networking sites ought to be banned.
I did have a profile on MySpace, but it was never used for things other than messages which could have quite easily been sent by email, or for stupid people calling me a {bleep}.
Most of my 'friends' there were people from school who I didn't like (and who didn't like me) so I just deleted it. I couldn't really see much point keeping in contact with them now I have left school.