redditor TheHerferd made this excellent watermelon carving. Using a potato peeler and a bird's beaked paring knife, he completed the project in under an hour.
Watermelons make great brains, especially if you can get some light inside for some extra glow: http://www.zogdo.com/ideas/carved-watermelon-skull-brain/
This looks like a lot of fun... you can't just slice a melon like that, you have to perform a commisurotomy and a frontal leucotomy then you can slice it.
Eh, Brain watermelons are so last season. Kicking into fall, how about a brain meatloaf? Sculpt something that isn't usually sculpted. :-) http://zombieslam.com/2011/05/i-feed-my-children-brains/
http://www.zogdo.com/ideas/carved-watermelon-skull-brain/
http://zombieslam.com/2011/05/i-feed-my-children-brains/