An open-hardware and software Gameboy flash-cart and hardware peripheral framework
The parts-list for easy ordering can be found on GoogleDocs
The firmware runs on the AT90USB1287 to emulate ROM/RAM reading/writing data to a microSD card formatted FAT32. It can be edited in Arduino IDE.
A menu runs on the Gameboy to choose the current ROM/RAM. When a ROM is chosen, the gameboy reboots using that ROM/RAM.
To compile, run
I used the Arduino SD library to read/write from SD card.
Thanks to Christopher Antonellis for good ideas, programming help, and generally being an awesome dude.