From http://www.musopen.com/html/about.html:

Musopen is an online music library of copyright free music (public domain music). We want to give the world access to music, without the legal hassles so common today. There is a great deal of music that has expired copyrights, but almost no recordings of this music is in the public domain. We aim to record or obtain recordings that have no copyrights so that our visitors may listen, re-use, or in any way enjoy music. Put simply, our mission is to set music free.

Musopen is a U.S. registered 501(c)(3) tax-deductible nonprofit charity. To verify our non-profit status, please click this link and search for Musopen