Gameboys are great fun for hacking on. There are open
source development
kits and languages out, the hardware is *very* well documented, and there
are tons of third party expansion and adapter cards.
[...]
Elektor magazine published a design (alas without the source code to the
firmware) for an audio-bandwidth digial storage 'scope card for the
Gameboy. No, I am not joking...
-tony