Yup, most of everything has been mentioned so far.
Umineko, Dead Angle. Probably one of the most played tracks in the game and it creates a pretty good atmosphere.
I/O, Subnetwork. Is pretty awesome.
Grisaia, A lot of tracks. But I'm forced to choose one so here it is. The energy coursing through one's body during this track is indescribably amazing.
Desire Dungeon, Can't find a specific one but this one has all of them. The music is probably one of the reasons I really like this game.
Chaos;Head, Cry (is what the youtube link says but I'm not sure about that). A good ED to that sort of end. Sorry about the lower quality.
Yume Miru Kusuri, To The World of Dreams. Not my favorite track, but still pretty awesome.
Demonbane, The Zero Escape Series, Hoshimemo, G-Senjou, Saya no Uta, Narcissu, and Rewrite all have pretty nice tracks, but most of the good ones have already been posted. Higurashi is pretty good, but I can't find any of the good tracks.