In addition to being the Visual Effects Art Director for films like Forrest Gump, Back to the Future II, The Mask and Terminator 2, Doug Chiang was head of the Art Department and Design Director for Star Wars Episodes I and II. His terrific production design art is featured prominently in the Art of Star Wars books for those movies.
The Doug Chiang Studio site is devoted largely to his own book and film project, Robota, and the galleries feature art from that project. You can order the book from Amazon and see teaser trailers here.
Kind of hidden in the current navigation is a section of Studio Tips, that step through the process of creating a concept design marker sketch and painting.
There is also a more general Doug Chang gallery on the Ice Blink Studios site.