This is NEVER going to happen. Several companies or groups have tried to come up with ways to permit this over the last couple of years, but none has ever come to fruition. The content industries absolutely hate hate HATE the used resale markets. There's no way on earth any offer of a fraction of a resale market would be sufficient to convince the music labels to throw away one of the biggest "advantages" of digital from their point of view. http://www.teleread.com/copy-right/digital-dj-vu-redigi-pledges-to-allow-resale-of-used-mp3s/

Amazing. I was able to guess almost the exact content of this post from seeing the headline on Twitter. :)