Besides all of the free royalty free music we give away for personal and commercial use here
http://www.partnersinrhyme.com/pir/free_music_loops.shtml
we also like to point you to other websites and blogs that offer free royalty free music. Here are three composers that I ran across today:

Taylor Howard
http://www.taylorhayward.org/recordings.htm
Some very nice ambient / classical piano recordings from Taylor Howard with wide-open, copyright-free terms for use:
“The music on this site is: free to download and play, free to rebroadcast in any form for any purpose, free to play in public, free to publish for profit, and free to sample.
There is no copyright on this music.
If you can think of a creative way to use this music, you have my full support.”

Bill Cushman
http://ghostnotes.blogspot.com/
This talented is offering his beautiful piano pieces for free use in personal and commercial project. You need to contact the composer before using music.

Derek Audette
http://derekaudette.ottawaarts.com/music.php
A collection of free royalty free music from Derek Audette. Although most of the tracks are very midi sounding there are some interesting and usable pieces here:

“There is no charge or licensing fees associated with the use of any of these songs for any reason. I only ask that if you use them in a production in which you are able to give credit, (such as closing credits in a video or film production) that you do provide the proper credit in your production. ”