This project turns your Raspberry Pi into a portable gaming machine.
The touch screen LCD is connected using a special core running in a Guzunty programmable IO expander. This part of the project is explained here:
https://github.com/Guzunty/Pi/wiki/gz_lcd_driver-waveform
We used a LiPo battery for power, drawn though a small switched power supply by Meltwater:
http://pihw.wordpress.com/meltwaters-pi-hardware-kits/power-supply-kit/
The rest of the project is all software. We used a Wii remote to control the games, using a low cost bluetooth dongle obtainable at Dollar stores. The software used to receive the remote button presses was CWiid (http://abstrakraft.org/cwiid/). Finally, we used DGen (http://dgen.sourceforge.net) to run Sonic the Hedgehog. Sound output is through the Raspberry Pi audio jack. The LCD display driver is also compatible with MAME but we're still working on that to get the performance good enough.
Next job is to create a case for it. Suggestions welcome. :-)