I'm not sure how I missed this when it came out, as I'm a big fan of both eMusic and Pandora. It seems that Jon Strunk, a product manager at eMusic, has created a terrific Pandora/eMusic mashup.

All the details can be found on Jon's blog, but the service works as you'd expect. While Pandora plays tracks, eMusic offers them up for download (if they're available). Because I have both Pandora and eMusic accounts, when I first visited the mashup I was auto-magically signed in to both services and my default station started playing. Genius.