I know Yac started a thread on this...oh, two years ago, but it's finally nearing completion. They've even got a demo of the Creature Creator expansion that allows you (like Build-A-Sim) to make Creatures off-game and upload them to the Sporepedia.
Check it out:
http://www.spore.com/
I downloaded the demo, and started making creatures immediately. After you've created them, you can take them to a 'test drive' area, where you can take pics of them. Here are some of miy creations:
The Dougner:
The Malkii:
The Jasetor: