Many people buy now various content online (e.g. via the apple store or an eBook from amazon), which was in former days bought via DVDs or CDs. This makes it quite hard or even impossible to resell it. Amazon (in 2009) and now also Apple are already thinking about this problem, and both companies handed in patents (see: 20130060615, 20130060616 and 20130060661, under the title Managing access to digital content items) with models to resell digital content such as videos, eBooks, games or music.
Apple describes in its patents a system which allows the direct transfer of digital content between users. The person selling the content automatically loses access on this content, which is managed by a system – e.g. the iTunes music store or the amazon platform. It is also foreseen in this model, that next to the selling person also the copyright owner shall receive a share, besides the content is passed on for free.