Check out the Spore creature creator which is available today from Maxis here

You can actually create whatever creature you are going to start the game using because the system allows you to save the creatures you make and then import them into the whole game once it is released. This means we can all play around with the highly anticipated editor now, and have more time to explore procedurally generated planets and fight against AIs when we actually get our hands on the game.

You can see I made a cute little Zergling. I just saw a video that was totally insane where a person made a creature that looks like two people having sex. Simply by putting on 4 arms, 4 legs, and 2 heads and having the two bodies connected by a thin tube. It's pretty much win when he has them get excited or scared. See what you can create and have fun.