Recipe(tried): Rocket cake

A rocket ship cake is very easy to make. Make a sheet cake, frost it with blue. Long ways on the cake, outline a rocket in white with an outline tip. Fill the shape in with white icing. The easiest rocket to do is basically a long triangular shape with afterburners at the bottom and supports on each side of the bottom. Decorate the rocket with US1997 (for your son's birthdate) or with his name. You can also do a tiny flag on it in icing. Use a darker color of icing for the afterburners and supports, red and blue are always cute. Don't be too worried about the details, just a suggestion in icing is enough.
You only need a decorating bag, a small outline tip, a round tip, and food coloring. A buttercream icing is easy to work with, or you could buy an already made white icing and color portions of it. For a regular sheet cake you'd need two containers of icing to be sure to have enough, or make 1 1/2 recipes of your favorite.