I've been geeking out pretty hard about Spore ever since I heard about it over a year ago. In an attempt to populate the Spore world with some serious ridiculous creatures, Maxis has released a demo and a paid, full version of their creature creator. I spent hours last night messing around with it, and made a number of ridiculous creations, including the little guy you see above you. I named him Goreno as a tribute to this site. Hopefully, I didn't save over him.
Part of what I think is going to make this game so spectacular is the social concepts of sharing your creations. Out of the box, the creature creator has options to send photos of your creations and direct upload videos to YouTube. Within the game, the Sporepedia lets you look at other's creations as well as share your own. You are also given a MySpore page that will eventually allow you to keep in touch with other Spore users. It appears that after years of delays, Spore is very ready to come out and will hopefully live up to all expectations.
While you wait for the Creature Creator to download, check out this awesome Minotaur someone made!