Craftster user Umbrolly cooked this magnificent Tardis cake for her sister's birthday. Apparently the eerie Martian planetscape beneath the tardis was meant to be a nice smooth rectangular cake but went wrong -- I think it makes the whole thing just perfect. Lots of documentation on Craftster if you want to try your hand at it.
Link (via Craft)
It looks really wobbily in these pictures, I used a different cake recepie to usual and it was a bit too moist, so what started out nice and rectangular went sort of squishy.