Mixkit

Claim-free and completely free-to-use BGM and sound effects — safe for YouTube creators.

SoundGator.com - Free Sound Effects

Freesound: collaborative database of creative-commons licensed sound for musicians and sound lovers. Have you freed your sound today?

SoundBible.com offers free sound clips for download in either wav or mp3 format. We offer free and royalty free sound effects and clips for video editors, movie scores, .......

MediaCollege.com is a free resource site, suitable for anyone with an interest in audio-visual media. Tutorials and articles include everything from video production to website design.

ccMixter A music community site operated by ArtisTech Media -- founded by Creative Commons