I took my Raspberry Pi, a case from Adafruit, and a box from Hobby Lobby and made this:
The box has enough room for the Xbox 360 Controller, Xbox charge cable, wireless receiver, micro usb cable, and power supply.
I painted the box yellow and let it dry. Then I used a projector to trace the question block logo off of Super Mario Brothers onto a folder and cut it out. I did the dark grey first and let it dry overnight. Once it was dry I did the orange.
It runs RetroPie (http://blog.petrockblock.com/retropie/).
Currently it has NES, SNES, and SEGA emulators. It uses an xbox wireless receiver and a 360 controller to play the games.
For more information including a demo video, check out: http://dustinevans.net/retropie.php