if you’ve got a gameboy advance, a gba flash cartridge, and a gps receiver that outputs nmea, then you can turn your gameboy advance into a cool gps mapping receiver.
mikhail sharonov created a nice litle application that assists you in importing and calibrating up to 20 raster maps. the software will then output a gba rom file that you can run on your device. with a few minor software updates, he was also able to get the microsoft branded gps to work (the one which comes with microsoft streets and trips 2005). hot!