There's no reason why the space saving concept of the bunk bed can't be applied elsewhere. Desks, cribs, outhouses--you can save a lot of room with just vertical stacking. People at the i3 Detroit hackerspace built these bunk couches.
As with beds, the top bunk is the least comfortable. With nowhere to rest your feet, you really can't take the pressure from the couch cushion off the back of your legs, or relax your thighs forming a platform for your laptop.
Is that a satellite dish to the side of the guy on the right?
Is that a satellite dish to the side of the guy on the right?