Yes, Pegasus is right, Psych Central is the best of the lot. But if you want to prove that to yourself, here's a list of links to other sites I've investigated in the past before sticking with PC:

http://www.mentalhelp.net/

http://www.mentalhealth-world.org.uk/forums/

http://www.psychnet-uk.com/index.html

http://www.moodgarden.org/index.htm

http://www.anxietytribe.com/

Good luck!