National Wildlife Federation
This nifty site lets you mix up animal body parts to create your own bizare species and test your tracking ability by identifying prints. It also features fun facts that will allow you to amaze your friends in the section entitled "I Didn't Know That!"

Yuckiest Site on the Internet
This is science the way you loved it when you were a kid - YUCKIE! Ask Wendell the cartoon worm questions. Or just check out their gross science stuff (it even includes the sounds of roaches rustling).