associating sounds with program events

I don't believe there is a way native to OS X to assign a sound to a particular system function such as a new mail alert or emptying the trash. Does anyone know of a utility that will add this function preferably using a WAV or MP3?
Thanks
ED

there are ways of doing this, in mail, it already has a set of sounds it uses, many other apps have their own sound areas built in. my preferred way isMooSB