Oo, Audacity is awesome.
I made them use it (ok, I use it) at the church for sound
files, too.

Layers are so much fun to fiddle with. That's a really
good one to do it with, too.
Garageband is awesome, too, but it's a Mac-only program.
And I think Audacity is simpler to understand.

Oooooh edit songs! You are too smart.
I hate tracks with scads of space in the middle and a tag
sort of song at the end. Bleah. I might just do that
myself with a few...marvelous idea.