How about a 3d version of this, where you have to hit a moving target. You know it makes sense!

Of course, you might want to have a think about the DGDev team of winners who are planning to write some sort of game. Or something. Various threads about this are peppered throughout the forums - here are a few (you might have to wade through a bit of off-topic stuff, but that's half the fun!):

one
two
three

There may be others too - it's kinda hard to follow