This sounds like such fun!
My favorite Apple II emulator is Virtual II precisely because of all the wonderful disk and computer noises :)
If a whole other board would need to be created to support the disk sounds, please allow me to day-dream a bit.
1. Perhaps if the computer is communicating over the serial port at 110 cps, we could hear a paper punch machine?
2. If the computer is using the audio jacks maybe would could either hear the actual audio or even a simulation would be fun and educational. My younglings have a hard enough time with the cassette player itself ;)
3. An for the coup de gras, lifting the stop switch while toggling the right aux switch could play "Fool on the Hill"?
Maybe a fortunate owner of an original Altair could re-create this classic demonstration and record the goodness.
Probably a little silly in a thread where folks are longing for a real interface to a real floppy drive :P