With FindSounds you can easily do a search for particular sounds on the internet.
FindSounds.com is a free site for finding sound effects and musical instrument samples on the Web. It is a Web search engine, like Google and AltaVista, but with a focus on sounds. It provides powerful features, yet is simple and easy to use, and suitable for all ages. Note to parents: audio files containing obscenities are filtered out so this site is safe for children.
You can search for AIFF, AU and WAVE files of specific quality and size in many different categories. Give it a try!