Facebook might hate freedom, but it's still going strong here.
Law enforcement gun advertisement posters. Some of them, especially HK ones, are pretty cool.Have them framed though, it looks so much nicer than just tacks in the wall.
Cover the walls with this http://www.dreamstime.com/camouflage-netting-thumb1895476.jpg and hang guns on one wall and gear on the opposite wall. Don't forget the tv and game system. Right next to mini fridge. Find a comfy couch and you're set.