Right now it seems the fancy theme cakes are really hot.. the ones covered in that fondant (not sure on the spelling?)
but personally i think the ones you can transfer photos to icing are super fun.. but a good butter cream frosting just cant be beat.
At diff parties ive been to latley they seem to have cakes that are a twist on old faves. Choc cake with a fudge layer in the middle, vanilla with raspberries etc..
thats all i can think of this early in the morning.