I've been in UbuntuForums as well, but I found that this general forum site got me totally hooked, because it is a pretty great and covers a broad range of topics. Additionally, I've found that I go to SocialDiscussion a whole lot more than UbuntuForums, due to the fact that UF is just basically all technology talk, which I'm not really into.
Anyways, I really fell in love with SD:P