My daughter wanted a snake cake for her birthday and amazingly enough, the local Giant Eagle had an edible image of one! I think it turned out great and Michaela loved it- so much that she wouldn't let me cut into the snake part yet :P
Sorry about the cruddy picture but you get the idea.
And yes, the snake is purple and greenish.
http://i239.photobucket.com/albums/f...9_09150074.jpg