A few friends of mine came up with the idea of throwing glitter on your paint while it's still wet and then clearcoating over it. In the end it looks pretty good, but be warned it's difficult to evenly distribute the glitter and is easiest to do with 2 people - one spraying and one applying glitter. I haven't tried it myself but have seen the end result, and it was pretty cool.

Also, if you have a lugged frame there are all sorts of cool color combo possibilities if you feel like taking the time to mask off the lugs and do different sections different colors.