Lushprojects has a pong playing hat (also displays text, and plays space invaders) – “For the display I used 5×7 LED modules from HP. They were cheap on eBay! The project drives two 21×10 dot displays each made from 6 LED modules. Control is provided by an AVR ATMEGA32L microcontroller. First job was to prototype the hardware on breadboard and do some very simple software…” [via] – Link.