In anticipation of Spore, EA has released the Spore Creature Creator (as either a free trial, or for 10$ you have more creature options) so you can get started making your creatures for the September release of the game. It’s really well done and more fun than you would think.
You can also share your creatures, and import other creatures from Sporepedia.
You can check out my latest creatures here. I can’t wait to get these guys out into the world!