http://www.youtube.com/watch?v=vf0I5s-Ghhk
According to Boing Boing:
This is music made by four postal workers as they cancel postage! When I listen carefully, I think I can actually hear the spring mechanisms as the stamps hit the ink. I love it as an example of music turning what is normally seen as a boring, repetitive task into something this joyful.
Mesmerizing.