I've always heard that you can add a can of Diet Sprite or Diet Coke to a cake mix and it makes it wonderful and low fat, this photo and link below shows how to make strawberry cupcakes for less than 100 calories each. This recipe is for strawberry, but think about the other options you could do....
Vanilla Cake Mix with Diet Orange Sunkist for a yummy Dream Sickle flavor
Lemon Cake Mix with Diet Sprite and add some lemon juice or zest for extra flavor
Chocolate Cake Mix with Diet Coke
Cherry Cake Mix with Diet Dr. Pepper
|Image and recipe from here|