http://titania.student.utwente.nl/rockbox/

The upcoming port of rockbox (Open source firmware, first introduced on archos products) to the iRiver HDD players will feature a gameboy emulator plugin based on GNUBoy. It now runs full speed (or almost ? It's very much WIP), has full 2-bit grayscale graphics, and is just plain sexy in the geekiest possible way ! Of course the LCD has shitty response times and the unit can only register 1 button press at a time - but (sorry for the bragging / borderline troll :)) try and do that with your sucky iPod !!