There are several websites where you will find audio resources of different types and licenses. Some of them are listed here:
http://soundbible.com: This site offers a wide variety of sound bites, sound clips, and sound effects with different license types such as Public Domain, Attribution 3.0, Attr-Noncommercial 3.0, Sampling Plus 1.0, and N oncommercial 3.0.
http://www.partnersinrhyme.com: This website has an interesting database of free sound effects, music, videos, MIDI files. It also provides collections of paid music of different genres of music.
http://www.pacdv.com/sounds: Even though this site contains a short database of files, it provides high-quality, free, and very useful resources.
http://www.freesound.org: This site contains a variety of Public Domain, Attribution, and Attribution Non-Commercial licensed audio resources. Here, you will also find a very active forum with information on how to create your own audio, sample requests, or even legal information...