What do you see when you look up from your desk? In the best of all possible worlds it's the room you are working in because that's the optimum Feng Shui. It's the 'command position' (provided you aren't in line with the entrance) because you can simply look up and see anyone who enters or exits. Yes, there are 'cures' if your back is to the door (most notably a mirror positioned at eye level) but that's not our concern today.
Many people look up and see a wall. For easy access to frequently used material they put up a bulletin board and attach business cards and instructions. I think it's better to have a thin reference binder where you place frequently accessed material in sheet protectors. You can purchase a utilitarian binder at a big office supply store or go crazy and get something fun by surfing the net. I found these with one click when I did a Google search for 'fun binders.'
You could then use that wall space for small items that might otherwise clog your desk. This is a new product from The Container Store and I must say it made me smile. A million years ago I bought one just like this in NYC at the Bloomingdale's on Lexington Avenue. It was canary yellow and they were all the rage. It served me for years. If you try something like this just remember to keep it tidy and make it serve you. Otherwise every time you look up to think you'll be confronted with chaos. Our goal as Zen Organizerstm is to create peace and tranquility. We're trying to tame the wild monkey of our mind not feed it crack.