You could also make a roman numeral, hexidecimal or binary clock perhaps?

Or something that looked like the predators arm band counting down maybe

Hey...

If you turn on and off the lights really quickly you might be able to get "shades"

you could display greyscale images by having it so the brighter their color, the longer they stay on.

You could do something like have 10 shades of grey and break your time up into 10ms or 100ms chunks (not sure what would look the best, youd have to play with it)

so if it was a 100ms time chunk, every 10ms your code would update the display...

0 = always off
1 = on for 1 tick, off for 9
2 = on for 2 ticks, off for 8
...
9 = on for 9 ticks, off for 1
10 = on for all 10 ticks

ya get what i mean?

being able to show "greyscale" might let you do some interesting stuff

game of life, or any other cellular automata?