rain

This is a cheap rip off of rain(6) from BSD.

M-x rain RET to start raining
M-x rain-stop RET to stop raining

Note: rain.el is timer driven and thus it will keep raining even
when you bury the buffer.  I'm not really sure how to implement a
clean way to stop it.  Bind all keys to rain-stop?  Use sit-for
with a big value or with a loop and quit when it returns?