These guys have something special... Note: this music won't necessarily sound amazing in the sober light of day, but listening to it on spice journeys has ALWAYS resulted in deeply spiritual visions, both for me and others! It's great when you're stoned, too, but when combined with DMT it's somehow a direct link to God and the root of human consciousness-- even more so than a normal DMT experience.
The combination of Om and DMT has single-handedly made me and a friend realize the necessity of pursuing a spiritual lifestyle, and realize it more immediately (as in let's go move to a hermitage in the desert tomorrow) than ever before.

Cremation Ghat I & II are pretty awesome,
so is At Giza
I can't quite listen to On The Mountain at Dawn when not under the influence of something,
but with spice made me want to crap my pants with happiness.
Check it out!

Agreed.

Om is a great band.
http://www.youtube.com/watch?v=lG_QOmjP4VU

Pilgrimage is a prime album.


EDIT:
Those others who enjoy this type of stuff, Sleep is the old band of one of the two persons in Om.
Here is one my favorites of theirs:

http://www.youtube.com/watch?v=zj9IAvv32wE


Ride the dragon toward the crimson eye