This company Cook & Becker has been commissioned by Naughty Dog to produce some museum quality art prints of images from and about The Last Of Us. Some of it is concept art, which I think I may even prefer. Others are straight shots pulled right from the game world.
They also do a few other games too. There's some really cool images from Journey in there. I love the Journey 2-D level map.
They're expensive, but I'm totally considering buying something. They're good size. They're only in a limited quantity. They'd be totally unique. And they can in most cases stand up as individual works on their own accord. I'd stay away from anything with too much branding on it, or anything with any heavy focus on the particular characters. But it's all really cool imagery.