A repository of sound effects (some of them have been used in Hollywood movies!). The CC licenses are in plain sight for each sound.
Posts in Category
A huge catalog of sound effects. Very clear attribution for all the sounds (which are mostly CC BY and public domain).
A great, curated collection of electronic music. You can search by music type (like dubstep, house, hip hop) and also by license (attribution, share alike, etc.). There are ads on this site, and some of them look like download buttons, so be careful. This site also has a good database of sound effects. Even a…
A nice repository for game art, game music, and game sound effects. This site features a filter by Creative Commons license, too! http://opengameart.org/