I saw this picture on the blog Glorious Treats, and was inspired to try this myself.
<--- Amazing perfect rainbow jello
Here is my version:
<--- My inferior, but not terribly bad version
It took forever to make, but it turned out quite pretty, I think. It would have been better if I'd had those dessert glasses, but I had to make do with "crystal" plastic cups. I followed the recipe pretty closely, except that I added 1/2 teaspoon of unflavored gelatin to each layer in order to give it a little more firmness. I'm pretty pleased with the results, even though my layers aren't very even. Oh well, it still tasted good!
Here is the recipe if you want to give it a go.