What’s That Sound? Learning to Listen and Identify Sounds on the App Store on iTunes
FindSounds - Search the Web for Sounds
Web-based search for a variety of sounds
Freesound.org - Freesound.org
Freesound: collaborative database of creative-commons licensed sound for musicians and sound lovers. Have you freed your sound today?
Free Sound Effects | SoundBible.com
SoundBible.com has thousands of free sound effects for everyone. Browse our extensive sound library and pick and choose the sounds you want. Sounds are updated 3x a week or...