Emily from Tangible Pursuits shows how to make a hanging letter organizer to help control the clutter at your desk. It would also be a good clutter buster by a back door. The organizer has two pockets to hold mail, magazines, or other paperwork. You could designate one for incoming and one for outgoing, or maybe one pocket each for you and a spouse or child. The back is supported with some plastic canvas so it will keep its shape. Go to Tangible Pursuits for the tutorial.
[photo from Tangible Pursuits]