Great thread, Lenny.
There are many creators of music (who you should know).
More-a-less, here are a few names of groups that rule:

[Experimental and Metal]:
Godspeed You Black Emperor!, Battlefields, Explosions
in the Sky, Envy (the shoegaze/metal group from Japan),
Dispensing of False Halos, Pelican, Sickoakes.

[Ambient/Electronica]:
Boards of Canada, Global Communication, Windy & Carl,
Slowdive.

[Indie/Rock]:
Vast, The Flaming Lips, Neutral Milk Hotel,
My Bloody Valentine.