John Eaves also recently wrote an article for StarTrek.com, sharing some of his artwork from Into Darkness, including designs for the Nibiru and their weapons, and a "dark phaser". Here are a couple of examples, you can see and read more, on StarTrek.com:
UPDATE: Another artist that worked on the film, Maurico Ruiz, has also posted some examples of his work, including designs for Scotty's fishy friend, and other wildlife, plus many options for more exotic looks for Kirk's twin companions. Here are a few examples, see more on Ruiz's portfolio:
Elsewhere in the nuTrek universe, Concept Art World have run a couple of features on concept art from Star Trek: The Video Game, featuring work from artists Mike Sebalj and Thomas Pringle. Here (continuing after the jump) are some of my favourites from those selections, while you'll see much more if you click through to the respective articles:
To check out some more production artwork, go here, or here, for Into Darkness, and here, and here, for more from the video game.