Creative Commons is a nonprofit organization that enables the sharing and use of creativity and knowledge through free legal tools. The tools available give everyone from individual creators to large companies and institutions a simple, standardized way to keep their copyright while allowing certain uses of their work — a “some rights reserved” approach to copyright — which makes their creative, educational, and scientific content instantly more compatible with the full potential of the internet.
Authors can choose one of six different license conditions, covering the spectrum of possibilities between full copyright - all rights reserved - and the public domain - no rights reserved.
Find CC Material on the Creative Commons site.
Flickr: Creative Commons --contains many cc licensed photos
ccMixter --contains many cc licensed music mixes
Jamendo --another platform for cc licensed music
Freesound--provides cc licensed sound samples
YouTube --how to access and/or upload cc videos on youtube