Have you heard of Musopen? It’s a site which is working on providing completely free copies of classical music scores, as well as recordings. They are still teething, but already have the complete Beethoven piano sonatas available. One of the most interesting features is that you can contribute funds toward the publishing of new pieces. When enough money has been raised, they will get a professional to play and record the piece. For example, the Goldberg variations are currently 34% funded.
For pieces which have both a score and audio recording available you can read the score while listening along. Currently this is done in a very basic flipping-the-pages kind of way, but it has a lot of potential. I’d personally love to have a recording in which each group of instruments has been miced individually, accessible through an interface in which you can turn them all off or on at will. With ordinary commercial recordings that would never fly, but if the music has been paid for in the public domain, no problem.
The really fascinating part of this endeavor is that for almost all classical music the copyright has long expired, but even though this is the case there are not freely available versions of the music. An organization which patches up this situation is well overdue, and I’m pretty excited and hopeful to see how this project proceeds. You kick arse, Musopen!