A colleague of mine spent the summer revamping his music curriculum to infuse as much technology as possible and found some great sites.
http://www.smartmusic.com/default.aspx: I wish this site was around when I was learning to play. I had to find a tape of my piece and play along with it. This site does that searching for you. It even tells you what you did wrong and it also logs your practicing. There is a subscription fee.
http://www.pandora.com/: This site creates radio stations for you based on your preferences. You can listen to it from your computer or cell phone. The site is free.
Clarification of Fair Use Guidelines of the Copyright Law
Finally The End To Copyright Confusion Has Arrived