Free Software: sfxr – glitchy games effects generator
sfxr is a tiny little tool built for the purpose of quickly generating unique, but recognizably stock sounds for games, specifically games competitions, where dev time can be measured in hours.
Derek Yu used it to create sound effects for the rogueish treasure platformer Spelunky. Generated sound effects for a procedurally generated game. For me, of course, it’s just a fun little thing to play around with and make stupid noises.