Use drawer slides; mount the drawer on the wall; attach the shell to the slides, so it pulls out. Shifty Desk / Hallway Stand by Daniel Schofield This is such a great storage idea! It can be a shelf and a drawer.
The Lattice Window Box w/ Cleat Mounting System. You simply mount the cleat to your wall and hang the box off the cleat. The cleat is recessed inside the back of the box wall for easy mounting flush to your wall.