You asked for " Any ideas" you didn't say they had to be practical

But if you lack creativity and want people to tell you how to refinish your alloy wheels then why not start a poll....?
Everyone loves a poll....

Seriously though, what colour is your car? You could colour code them, it's a pain masking up 4 wheels but look good when done. As stated crackle finish is the new "scene" thing as seen in PVW on that mk3 1.8T. Or you could go lairy and paint them dayglo, contrast etc. But ultimately look around you, you can get insperation from the strangest places...