Using a minimalist-Arduino circuit and four external buttons, Chuck has created a simple game-show buzzer system for four players. The first person to press their button illuminates a matching LED, and the remaining players are ignored until reset is pressed. This would be great for trivia nights or as a design foundation for something more elaborate - perhaps this project and four DMDs could be used to recreate "Sale of the Century". Nevertheless, it's a fun project and could be built in a short afternoon.
When making your own game-show system or other Arduino-embedded projects, consider our Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for sound effects and knock detection: