From HungryGirl.com:

You can actually click on this Web site and create your very own personalized cereal, choosing from over 40 all-natural ingredients. Then you get to name it, have it shipped to your door… and eventually CHEW IT! The best part is that you can watch the nutritional info change as you build it. FANTASTIC!

Hungry Girl also mentions you can do the same thing with bars and shakes at youbars.com, and you can make your own personalized bottle of Jones Soda at every Wal-Mart photo center in the U.S.!

- Rebecca