Blue LED Matrix Display
This is a cool little project designed by Ryan O'Hara: The Blue LED Matrix Display. It combines a MAX7219 and a 64 Blue LED panel so you can do animations, graphics, etc, with a simple 3-wire serial interface. The other cool thing is that each matrix has a set of connectors so multiple matrices can be combined into a single panel (up to 16 matrices).
Ryan did a demo video, which shows it off well. It comes pre-assembled, you just need to solder on the included pin headers / sockets.
There's more info on the project page - www.gadgetgangster.com/282