Off the top of my head, some of these mentioned already:
Tricky
Massive Attack
Portishead
Unkle
Hardfloor
Kid Koala
Air
Royksopp
Infected Mushroom
Lords Of Acid
Mystery Of the Yetti
Shpongle
Celtic Cross
Faithless
Lemon Jelly
Groove Armada

Bit of everything there really, downtempo/techno/trance/trip hop/acid house/electro.. etc...