How about the snake lemma? It's not a formula, but it could still look great on a cake! Plenty of excellent .tex diagrams here: http://tex.stackexchange.com/questions/3892/how-do-you-draw-the-snake-arrow-for-the-connecting-homomorphism-in-the-snake-l

How about the snake lemma? It's not a formula, but it could still look great on a cake! Plenty of excellent .tex diagrams here: https://tex.stackexchange.com/questions/3892/how-do-you-draw-the-snake-arrow-for-the-connecting-homomorphism-in-the-snake-l