I am the lord of the chill.
Got literally 1000's of top chill tunes (CD, vinyl, mp3)
Oh, you want a list . . . aaahhh!
Umm, here's a few suggestions of the top of my head:
Pete Namlook / Fax label (David Moufang, Robert Musso, Dr Atmo, etc)
Bill Laswell / Axiom label (check out collaborations with Jah Wobble)
Spacetime Continuum (Jonah Sharp)
Woob / Emit label
Makyo / Silent label
Feed Your Head compils (Planet Dog label)
A Reminiscent Drive
Sounds From The Ground / Sound Information label
Further - 5 Further Journeys
Irresistible Force / Mixmaster Morris / Rising High label
Endless amounts of Ambient Dub (Banco De Gaia, Higher Intelligence Agency, Suns of Arqa, Sub Dub, Scorn, Children of Dub, Drome, We, Sandoz, Digidub, Children of the Bong, Unitone Hi-Fi, Original Rockers, Trauma Club, etc etc)
Plenty of the above aforementioned also (esp. Brian Eno, but most of the rest of those artists aren't essentially classed as chill-out, just the occasional trax only)
Of course, it also depends on what you class as chill-out . . .
To some people, it's anything slower than ~130bpm
To others it's jazz-derivatives, or dub, or beatless ambient,
and then there's the global/world scene (Transglobal Underground, Loop Guru, Makyo, Afro Celt Sound System, Mo Boma, etc etc)
Then there's folk/hippy chill from the late 60's to mid 70's.
Some chill to mellow drum & bass, others to mellow rock . . .
whereas others are strictly classical, baroque 'n roll, hehe.
Then again, I can chill to almost anything:
Hawkwind, Porcupine Tree, Joy Division, Future Sound of London, Dead Can Dance, Durutti Column, Delerium, Adiemus, Seefeel, Autechre, Thievery Corp., Unkle, Massive Attack, Coil, Mouse On Mars, Goldfrapp, Astralasia, Peter Gabriel, Little Axe, Pat Metheny, Can, Camel, Kitaro, Hillage, Floyd . . . you name it, I've crashed out to it, lol.
Now, as for specific trax . . .