A quick video of something I did a while ago (ignore the scruffy looking bloke). http://www.youtube.com/watch?v=69xB5zqPUCg
Unfortunately the video does not show the colours of the leds which are a random mix of red, blue & white. There are 640 leds, switched in 32 groups of 20 and the whole thing only takes three pins of the Arduino for the clock & data lines to the M5451 chip & one for the interrupt input from the handle. The outputs of the M5451 are buffered with pnp transistors to increase the current capacity and also changes the outputs to current sources instead of sinks. This exhibit seems to be very popular with young kids, as does any display with a handle that they can try and turn at supersonic speeds.