I use to work at a movie theater so I ended up owning a shit ton of posters. One wall of my bedroom was dedicated to horror movies, one to comedies, and another one that was sort of a mix of whatever. I have taken most of them down now, though. All that remains is a Fellowship of the Ring poster above my computer and a Tenacious D in the Pick of Destiny one on the back of my door.
I have a fair few. I have the maps from Read Dead Redemption, Oblivion, Oblivion GOTY and Bully (I think I have one for Test Drive Unlimited in a drawer or something). I also have a Frontlines: Fuel of War posted (it game with the GOTY I got cheap, in a fan of that game's multiplayer), Command and Conquer: First Decade (Ion Laser!), Battlefield Bad Company and Mass Effect. I also have a couple Doctor Who posters, Star Trek comic posters, Simpsons Comic poster. In amongst all of this I also have the back cardboard from the box of my Street Fighter IV fightpad which features are of Akuma (though im not a real fan of Akuma I like its style).
Yep, the walls in my small study are adorned with a few pretty pictures:
A poster of the Dark Side of the Moon album cover made out of differently coloured coffee beans.
A poster of M.C. Escher's chessboard with ladders.
A framed poster of all main Mass Effect 2 characters.
A framed lithograph of the Mass Effect 2 Citadel.