Where can I find free sounds for my game?

I need some sound effects for my game. Where can I find some? Or any programs that can easily generate them?

ANSWER:-

This is the one I hit up the most: The Free Sound Project

Some others:

http://www.partnersinrhyme.com/pir/PIRsfx.shtml

http://www.pacdv.com/sounds/index.html

http://amazingsounds.iespana.es/en/