According to a wedding cake designer in Florida, you get a cake. At least that's according to Larry Bach, the owner of Sprinkles Custom Cakes in Winter Park, Florida. Though his bakery does far more wedding cakes, Mr. Bach admits that he has created a few cakes for women going through a divorce. The trend started about six years ago, and the bakery charges about $185 per cake.
So, a divorce cake? Why not? Not that I've ever experienced either event, but I would imagine that a divorce consumes as much energy as a wedding, if not more. You should mark the occasion in some big, and hopefully very tasty, way.