McFarlane Toys is releasing a boxed set based on "The Island of Dr. Hibbert" from "Treehouse of Horror XIII." It's got a release date of August 2007. There are more pictures at Spawn.com.
You can watch "The Island of Dr. Hibbert" below, thanks to the wonders of YouTube.
Also, I added a Manimals entry in the Super Simpsons Handbook today.