A ton of new concept art has come out from some recent superhero movies — most of it focusing on different character and costume designs, which didn't make it to the screen. Plus this totally amazing drawing of Tony Stark falling off Stark Tower while his Mark VII Iron Man armor snaps into place around him.
The Tony Stark image comes via concept artist Rodney Fuentebella, who also posted some "key frames" showing the Hulk fighting a jet on the Helicarrier, and Loki versus Captain America, and a couple other things. Here they are:
And meanwhile, artist Thomas Whitehouse posted some X-Men: First Class concept art, including some wildly different versions of the X-Men's early costumes. These super-colorful suits were inspired more by spacesuits or biker gear, and I'm not sure they would have worked quite as well on screen as what we eventually saw:
There's also a few images of Azazel's swords, plus the MIB Jet Hanger and the X-Mansion:
And finally, concept artist Steffen Reichstadt posted a ton of different versions of Stel, the Grendan Green Lantern who had a few moments of screen time in the big-screen Green Lantern movie: