This popular site serves up over 3,600 sound files and includes a search engine. WAV categories here include cinema, TV, sound effects, computer system events, politics, humor and more.
Soundsnap is an amazing opensource sound resource. You can sort by category, popularity, number or downloads, and more. According to the website, "Soundsnap is the best platform to find and share free sound effects and loops- legally. It is a collection of original sounds made or recorded by its users, and not songs or sound FX found on commercial libraries or sample CD's."