Television Without Pity: I love the snarkiness and brutal honesty from the user
regarding films and tv shows
U2 Feedback: a u2/music/etc board
3 Fat Chicks On A Diet- for weight loss support
TelevisionWithoutPity since forever, even when they were MightyBigTV.
A USC fansite, WeAreSC.com -I'm a football fanatic.
OhNoTheyDidn't- Not really a forum but there is lots of snarky commentary.
sickpuppiesworldcrew.net (For the Australian band Sick Puppies)
yesssaid.com/forum (A Tori Amos/Kate Bush forum)
Otherwise I just get my fix on LiveJournal.
The only other forum I read and post on regularly is a music forum which is local to my area. I spend a lot less time on there since I discovered Specktra a few years ago.