We built a giant LED board, about 6.5x6.5 feet, with 900 LEDs using ping-pong balls as diffusers. It can play Conway's Game of Life, Pong, and Sketch mode that allows you to create a starting pattern for Life. We output board state information to a MIDI board that allows us to make music based on what is displayed. This gets interesting with Life, creating minimalist generative music.
See it in action here: www.youtube.com/watch?v=Zu5ORo3Im1g
Thanks to Evil Mad Scientists for their Peggy 2.0, upon which we based the circuit for our project.