Jamendo has over 10000 albums of music which can be copied, distributed and played under creative commons licences.
Browse for music via tags or artists, or search. Jamendo provides handy widgets to share music on websites and blogs and they take care of the attribution requirement for you, by automatically displaying the creator's name and the title of the track. As you can see here.
Jamendo has a social network established around the content with members able to set up playlists, review albums and participate in forums. However, you do not have to register as a member to find, share and download music.
Jamendo : 21min20, thermostat 7 by En attendant Mado
I'm listening to this album while writing this post and enjoying it very much although it is in French and I have tres petite idea of what he is singing.