Flickr user raingirllori made a Cthulhu-themed cake:
Here is Cthulhu rising from the oceans, using a convenient little island with a tower on it to climb up. The base was cherry-chip cake, the island and tower a mix of cherry chip and yellow cake with chocolate frosting. Also used small chocolate 'pearls' as rocks. Cthulhu himself is all fondant, with two chocolate pearls that I seeped in red dye for eyes.