How often, as a teacher, did you struggle trying to find music clips that you can use in multimedia presentations? You try to consult the Copyright/Fair Use rules, but you’re an educator: not a lawyer! So what did you do? Either not put in an music or ignore law and do something illegal?
With CCMixter (http://www.ccmixter.org/), however, you can find some great music that you can freely use, mix, and put into your presentations. According to their website, CCMixter is:
a community music site featuring remixes licensed under Creative Commons where you can listen to, sample, mash-up, or interact with music in whatever way you want.
Obviously, they release much of the music, and others upload music, that falls in the Attribution and Non-Commercial Creative Commons license, so you can pretty much do anything with the music you find here, except for selling it. Just like any music/media, make sure you and/or your students cite the music as well. As with any music site, CCMixter contains A LOT of clips and full songs. You definitely need to spend some time here, but you should definitely find what you are looking for!