ccMixter Music Discovery:
Based on the ccMixter community site of CC-licensed remixes, samples, and songs, this resource has instrumental music, playlists, podcast music, and more than 1,000 free tracks that can be used in commercial projects.
Netlables at the Internet Archive:
This section of the phenomenal Internet Archive hosts music from small netlabels, many of whom put their entire catalogs under Creative Commons license. From exotica to indie rock to deep house, there are neatly 2,000 “sub-collections” of music with hundreds of tracks each. (And if you’re looking for true public domain music, the Internet Archive’s massive Audio Archive
is where you want to go.)
Free Music Archive:
Directed by the incredibly eclectic WFMU radio station, the Free Music Archive is a well-curated collection of MP3s pre-cleared for certain uses. The creators contributing to the FMA “feel that allowing a degree of free cultural access is beneficial not only to their own pursuits, but to our society as a whole.”