An album that came out quite some time ago, but did stir up a healthy buzz, seeing as it's connected to Radiohead, was Thom Yorke's The Eraser. It can now be downloaded at eMusic. You can sign up now, or test out the site by utilizing their FREE trial offer that will give you 25 mp3s.
Here's some of the more popular downloads at the moment:
thom yorke the eraser
john fogerty revival
beirut the flying club cup
broken social scene presents: kevin drew spirit if...
joni mitchell shine
There's also a new exclusive titled Daytrotter Sessions Vol. 1 which offers The National doing "Slow Show" and a handful of other artists.