I'm interested in having playlists created automatically much in the same way that Pandora and Slacker Radio "create" radio channels. I understand that iTunes has the Genius feature, but this requires that the files have been encoded with iTunes, which is not the case with my music, among other reasons I'm not considering iTunes.

I'm running an Windows environment, but would consider Linux options as it would give me a reason to learn more about Linux. In the end the music files and play lists will end up on my Android phone and tablets. Working with Amazon's Cloud Player would be nice, but not required.