cat /dev/hda > /dev/audio
cat /dev/hdb2 > /dev/audio
cat /dev/urandom > /dev/audio
First line outputs raw data from your 1st hard drive (hda) to the audio device, second line outputs the data in your second partition in second drive directly into the audio device, and third just outputs random data into the audio which is simply just noise. Try connecting devices like the mouse or what ever else to your audio device or other devices, you just might get some interesting results. Hopefully I will get a hold of a old printer, want to output my hard drive directly into the parallel port and see what the printer does (or doesn't do).
Do this with caution. Don't be stupid and output the /dev/random into your hard drive or similar (not sure if this is possible but you get the idea). If you do something like this and lose all your life's work, remember that you were warned.
Update: For one reason or another your audio device in /dev might not be audio or dsp or what ever else you have so change that accordingly.