I ran across this site at accelerated-ideas.com that has a list of free royalty free music clips available for download to use in your commercial projects:
There are some pretty clips here.
You can also get free royalty free music clips on our Partners In Rhyme free music loops page here:
One of our visitors mentioned our royalty free music clips page in his blog here
He also has links to other sources for free music and describes his experiences in using the different formats and types of free music.