The concept sketches from The Matrix by Geofrey "Geof" Darrow are beautiful, but almost too detailed. You can barely make out what the robots are made of. It would have been impossible to create them on-screen, but at least they can provided a framework. Sometimes, concept designers can go nuts with the design I guess.
Born October 21, 1955) Darrow is a comic artist and designer born in Cedar Rapids, Iowa, United States. He is known for having an extremely high level of detail in his work. He's worked on everything from the 80s show Superfriends to movies like Speed Racer and a ton of comic books.
Check out more of his work at the unofficial fansite http://www.geofdarrow.net/