Here is a site for the public sharing of sound effects. I have taken one so far for use in a video project.

http://www.soundsnap.com/browse

"License
You also hereby grant each user of the SoundSnap website a worldwide, royalty-free, non-exclusive, perpetual license (the SoundSnap License) to access your audio submissions through the website, and to use, reproduce, distribute, prepare derivative works of, display and perform such user submissions as permitted through the functionality of the website and under these Terms of Service.

Intellectual Property and License
SoundSnap respects and supports copyright laws and strongly believes that the creator’s creativity and originality must be protected and awarded. Also, we understand that the flow and dissemination of information, knowledge and art is for the best. For this reason, we have developed SoundSnap, a platform for the exchange of audio samples that may be used by the visitors of the website for their projects. You acknowledge and agree that all downloads from Soundsnap are governed by the Soundsnap License."