Inspired by Combinatorial Critters, and MonsterID, which allow you to create critters from combinations of parts, I just couldn't help but think, "That would be so much better as a web service", and thus the Critter Generator was born.
Now, as you will soon realize, I am not much of an artist, so if you want to take a crack at creating monster parts I'd love to update the service with some real art, and if anyone sends in another 'set' of parts I'll update the service to allow selecting among the sets sent in.
The source images are 300x500 PNGs with transparent backgrounds. There are five sets of images:
Where N is from 1 to 8. I then use ImageMagick to convert the full size originals into the three smaller sizes used by the web service. The source code listed off the project page also contains all the images if you want to get a feel for how they work. If you just want to peek at the source code for the service you can see it here.