There's a lot of really cool concept art in the portfolio of artist Stephan Martiniere, who was formerly a creative visual director at Midway Chicago and now an art director at Id Software. There's a lot of great stuff on his site, including concept art for stages from Mortal Kombat vs. DC Universe. The Bat Cave and the Fortress of Solitude are awesome.
One of the most interesting pieces is the first, a piece of art titled Hero. According to GameSetWatch, this is from an unannounced/unreleased game titled Hero. It's only one piece of concept art, but it looks like they were working on something cool.
There's other pieces from book and film in Martiniere's portfolio. Enjoy.