I'm on http://www.okcupid.com
Haha, mainly for the tests which are hillarious, and sometimes, very spookily true, about you.
So yeah, you run through tests, and using its special matching powers (its free), it links you up with people that may match with you, from your area.
Its pretty fun. It gives you a quiver, which is like a mailbox which updates with people it thinks would match with you