Christian Kim's DreiX shelf brings a little bit of the fairground to your living room, in the form of three spinning, rotating cubbyholes. His concept features three boxes. The central box is fixed to the wall and the other two are joined on by a pair of metal beams, which allow them to move around the central section whilst remaining upright.
You can choose to have the shelves lined up vertically, horizontally or diagonally, which is likely what gives it its name: DreiX translates to Three X. And you can even give the thing a yank and see where it ends up.
If these could be bought, I'd give one to the biggest OCD sufferer in my life. Not only could they worry about old-school obsessions like alphabetizing and color-coding their books, but now they would have to consider the books' weight to keep the shelves nicely balanced.
DreiX project page [Mocoloco via Oh Gizmo]