Once you find images for that multimedia project, you can breathe a sigh of relief. . . until you realize that you also need to find copyright-friendly music. Here are some great sites:

For music:
Jamendo "On Jamendo, artists allow anyone to download and share their music. It's free, legal, and unlimited."
ccMixter "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."
Soundzabound "Soundzabound Royalty Free Music supersedes Fair Use in that we fully license the music with unlimited rights for education and sign off that you are protected."
MelodyLoops "You can use Melody Loops as background for various multimedia applications: video games, educational software, Power Point and Keynote presentations, television advertisements, radio spots, documentaries, institutional & corporate advertising, hold on, jingles, websites, flashes, banners …etc. You can modify it as you wish. You may not resell or redistribute our music as we do it."
AudioFeeds "You are allowed to: download, copy, share, trade, distribute, and publicly perform (e.g. webcast) any of the files available in the feeds listed in our highly moderated database. All our feeds have agreed to the Music Sharing License available through Creative Commons."
FreePlay Music "For in-classroom student projects, the Freeplay Music Catalog is available for your use for FREE."

For sound effects:
The Recordist "The Recordist presents a collection of free sound effects in MP3 format. These sound effects are from The Recordist Private Collection library and the "Special Edition". The MP3 stereo versions are high quality 16 bit / 44.1kHz / 128K data rate compressed."
A1 Free Sound Effects