The best source for free legal music is probably Jamendo. Other good sites are Podsafeaudio, Opensound,  and ccMixter. An artist called Kevin MacLeod also lets you use his music for free as long as you credit him. Music distributed online (often under Creative Commons licenses) by Netlabels can be found here. Always check the license attached to the piece of music you wish to use and comply with its requirements.

Until early April 2008 downloading albums from Jamendo required installing e-Mule or BitTorrent. However, this is no longer necessary. There is a simple Download button. Note, however, that downloading an entire album can take a long time. Therefore, you may prefer listening to the music on the site and then downloading only the tracks you want

(Last revised November 17, 2008)