Sound

A1 Free Sound Effects

Sound effects for radio, weapons, household, animal, sports, television, weather, people, cartoon, vehicles, button, sirens and more. http://www.a1freesoundeffects.com/noflash.htm

FlashKit Sounds

High quality free sounds and music loops in mp3, wav, or flashtrak format in many categories including ambience, cartoon, communication, domestic, instruments, mechanical, nature, people, and transportation. Also offers several genres of music.
http://www.flashkit.com/loops

Partners InRhyme

Provides royalaty free music and sound effects plus free midi files, free sound effects, audio software and audio tutorials. http://www.partnersinrhyme.com/

Sound Central

"Free wav, midi, keyboard samples, audio programs for all platforms." Includes clips from cartoons, current artists, and more. Here you can listen to an alarm, nature sounds, clips of music, and more." http://www.soundcentral.com/