Same list from another similar thread:

Brian Eno (founding father of ambient music)
Deadbeat (electronic dub)
Amon Tobin (cinematic bigbeat/trip hop)
Red Snapper (processed acoustic breaks/trip hop)
Cinematic Orchestra (just download this man, you'll love it)
Bonobo (semi-acoustic, sample based triphop)
Boards of Canada (downtempo IDM)
Boombip (versatile electronic/breaks/folk/etc)
Portishead (founders of trip hop/bristol sound)
DJ Krush (Japanese instrumental hiphop, very cool and meditative)

Loadsa chilled out stuff in there man. Check it out.