Some of these are a little hard to define so it's hard to pin them down. So please don't correct me on any genres...
Advant-Gard Metal (Sleepytime Gorilla Museum, Diablo Swing Orchestra, etc.)
Alternative/kinda indie (The Red Paintings, The Dresden Dolls, Blonde Redhead....)
Alternative Metal (A Perfect Circle, Deftones, SlipKnot, Mushroomhead, Dir en grey...)
GothIC rock (not the same as goth rock--goth rock is like Bauhaus, Cure, etc. Gothic rock is more like Evanescence, Within Temptation, H.I.M., etc.)
Hard rock (Chevelle, Staind, Three Days Grace, Muse, etc.)
Industrial/gothic (Emilie Autumn, Psyclon Nine, She Wants Revenge, Blutengel, The Cruxshadows, Angelspit, Skinny Puppy...)
Industrial metal (Hanzel Und Gretyl, Rammstein, The Kovenant...)
Industrial rock (i.e. Orgy, Zeromancer, Marilyn Manson, L'ame Immortelle, NIN...)
Neo-Classical (Dark Sanctuary, Elend, Autumn Tears...)
Symphonic metal (Dimmu Borgir, Cradle of Filth, NightWish...)
Soundtracks (for movies, video games, etc.)