Phil Herlihy has written a tutorial for Adafruit in which he takes a Sega Game Gear handheld console and fits it out with all kinds of stuff, including a LiPo battery to power it and, of course, a Raspberry Pi for brains. Fantastic project, fully documented and one which I’d love to have a go at as I got hold of a Game Gear specifically to mod it for Pi. Phil has even exposed a USB port so you can plug a keyboard in, so it’s fully ready as a portable Pi! Read all about it here.