I found this a really cool idea: to use orange zest as an ice cream cup! It's cheap, easy to find and it will give a whole new face when serving ice cream at a dinner or special occasion.
You can also use passion fruit and even lemon. You just have to clean it well (take all the inside out), cut a sliver at the bottom so it can stand alone, and put it in the freezer until serving (so it gets stiff and also helps keeping the ice cream cool).
Photo: Real Simple