In a fairly surprising turn of events, Amazon is now offering DRM free MP3 downloads from the Nine Inch Nails catalog
. A total of 106 songs are available for purchase at the moment, for $0.89 and $0.99 each. You can buy full albums for less than their CD equivalents -- for example, Year Zero is $7.99 in MP3 format. This doesn't always work out, mind you, as Further Down the Spiral in MP3 is $9.49, though that EP is typically $7.99 whenever I see it in the store.
It should be pointed out that while Amazon will not sell MP3s with DRM, apparently select tracks from the service may contain watermarks applied before they receive the files.
Anyway, if you don't already own all the entire catalog, check this thing out. I think that you can thank Steve Jobs for taking one for the team to make this happen.