I am always on the hunt for music files, mp3 files, and sound sources in general on the web. These sites change so often that you really have to keep your bookmarks updated. I found a couple of new ones today in searching for materials for my upcoming conference presentations...try these out and see if you can use any of. I found several goodies that I will be using in the coming weeks.
Educational Cyber Playground Listings: http://www.edu-cyberpg.com/Music/waves.html
Free Kids Music: http://freekidsmusic.com/
Partners in Rhyme: http://www.partnersinrhyme.com/pir/PIRsfx.shtml