Heard loads over the years.
Heres a couple.
Orbital - Belfast
Massive Attack-Tear Drop
Massive Attack-Protection
Christina Aguilera-Beautiful (Chill Out Remix)
Madonna-Nothing Really Matters (Kruder & Dorfmeister mix)
Sub Sub - Past
Aphex Twin-We are the Music Makers
Salt Tank-Sargasso Sea
And one I heard last year which, is propably one of my fav chill tunes now:
Ryan Adam's version of Wonderwall, blissful and even Noel Gallager now says that Ryan now owns that track as his rendition is so good.
Havent heard it there but U2's Velvet Dress could be a good one too.