I am surprised nobody so far has mentioned the ultimate chill out CD ever, Kruder and Dorfmiester-KD Sessions.
I also just got done transfering about 10Gb of mainly chill shite from Europe, that is absolutely killa shite.
Ez3kiel
High Tone
Gotan Project
David Last
Crooklyn Dub International
Bourbonese Qualk
DJ Olive
DJ Wally (on Smoker's Delight)
Just a few of what I got all pretty great stuff. Also what everyone mentioned to Aphex Twins cool stuff can be a little dark, but I like that, FSOL on the more trippy eltro psyche, DJ Shadow's Endtroducing is another classic, I am also into DJ Krush like shadow though with hip-hop and japenese influence, Eno is brillant, but it is so damn hard to choose which discs to buy, Bill Laswell has produced and played in a ton of bands, his dub works are great also SXL a project that he was involved in, Oh I just a good one on the Global Underground label Afterhours, chill and little dark, 3 disc 2 music 1 DVD. There is a ton of stuff out there beside Smoker's and Zero7.