I think among these forums you'll mostly find metal, progressive rock, industrial and ambient stuff popular.
Biert Is Extraordinarily Rad & Terrific Twitter.com/Biert | D* | Proud member of the VVV "It's the unicorns paparazzi. They have finally found you and are coming to take you home, prince Biert." -- Faffy
Avant-Garde
Jazz
Noise
Experimental music
Drone
Prog Rock
Stoner/Sludge
Ambient
some early 90's blackmetal bands like burzum and darkthrone.
some pop music
and some metal bands(SYL, Mastodon, System Of A Down, Ministry. etc..)
Indie
Electronic
Dark Ambient
Metal
Jazz
Avant-Garde
Classical (Romantic period)
Rap
All kinds of rock
Those are my favorite genres. I basically listen to anything that isnt country, although I don't mind some of that either. Alternative Country (like Neko Case) is great shit.