The Open Game Art Bundle - Royalty Free Game Resourceshttp://open.commonly.cc/
I found this site that has some really good sound tracks, art and some other things. Worth checking out.
"... you can now download all the packages in this bundle under the public domain Creative Commons Zero license."
The Bundle at a glance:
From HalcyonicFalconX, the soundtracks from
Adventure Story, Bullet Heaven and Epic Battle Fantasy III.
From Jimp, art & animations from two never-before-seen games.
From NutcaseNightmare, soundtracks and the full source code
from Reimagine :The Game:.
From Stratkat, two videogame music albums
and a collection of music loops.
From Kenney, the debut of his Platformer Deluxe Tileset Pack.
From Mindchamber, art from Heavy Terror Machine,
Nightstrike and Da Pink Knight.