http://www.itr.ch/~reberhar/forge/
We know there are surfers who have those great visions of creating worlds of their own. The creator of this site decided to provide the once in a lifetime opportunity to specify of a world you want to create. Users start with world size and press the Submit button. After a brief pause a photorealistic image of your world, as seen from space, is returned to you. At the present time only random parameters are available, but it sounds like you may get more control in the future. Check back, or better yet e-mail the author to find out what is in store.