Planetocopia is a site by Chris Wayan. It consists of the maps and incredible paper mache models of the imaginary worlds he's built. Most of the worlds are variations of earth (axis rotated, poles flipped, seas turned into land and vice versa) or terraformed versions of Mars and Venus. Of use to other worldbuilders is Chris's application of geology, climatology, and biology to develop believable but very different ecosystems from our own.

The site can be found at http://www.worlddreambank.org/P/PLANETS.HTM

(Warning, Chris is either a furry or at least fond of anthropomorphic animals, some species pictures may be NSFW.)