A GREAT way to make a fish birthday cake! This site also describes a way to make a cute "aquarium" out of blue jello, using jelly-beans for "gravel" at the bottom. This would look AMAZING in a trifle bowl or an extra-deep rectangular glass baking dish!
Make kids' lunch fun with a hot dog "octopus." It would be fun to combine with reading a book about the ocean-- the kids could help make the book come to life! And if they helped make lunch, it wouldn't be such a challenge to get them to eat!