Dark Ambient: Lustmord, Gustaf Hildebrand, Robert Rich
"IDM": Aphex Twin(anything choosen from what I have) and Autechre
Metal: Burzum(filosofem), Xasthur, and mostly atmospheric BM
Industrial: Suicide Commando, VNV Nation, SPK
(Fin)NRG: Alek Szahala and Nomic
Classical: Bach, Handel, Liszt and Chopin
Demoscene music: Bitfellas radio
I will generally create a mix of from the above styles in a playlist and listen to it, when it begins to bother me (after some hours) I'll just change music style.
Also sometimes I just get some game CD and listen to the tracks, usually I choose Total Annihilation.