SwitchZoo (http://www.switchzoo.com)

At first you might think this is a simple "head of a bear, legs of a giraffe, tail of a crocodile" mix 'n' match game. It is, but there is more depth to it than that, as you'll see. Once you've gotten pretty good at the basics, you can step up the complexity by applying to be a zookeeper. You'll need to find 34 "hidden" animals around the site.

The site uses Flash, and there is an extensive "Help" section if you have problems displaying the animals. You can also title and print your pictures.