When I saw this on eCelebrating's blog, I nearly squeeled. The cuteness! The color-coordinating opportunities! The sense of why didn't I think of that?
Get thee to a store that sells a good variety of sprinkles, jimmies, and dragees (Try Sur la Table or Cakewalk Chicago), and you'll find that the possibilities are endless! eCelebrating gives some good tips on alternatives to ice-cream, if you'd like to go for a healthier option.