MusOpen.org: Public domain performances of public domain music

"Classical music itself, by virtue of being old, is mostly public domain, but recordings of performances are usually under copyright, and not many are available for use in free culture works. An emerging new resource, aiming to resolve this problem is MusOpen — a repository of public domain recordings of public domain music, available in Ogg Vorbis and FLAC formats."

http://fsmsh.com/3520

http://www.musopen.com/