This East Village Manhattan apartment, designed by No Roof Architects and featured in June's issue of Dwell, in a story entitled "A Narrow Victory," makes interesting use of only 640 square feet of space.
Storage under the bed and floor
This apartment combines two of my favorite design elements: making good use of small spaces and secret compartments. Because, really, why not use your floor as a storage space?
Some other innovative design featured in the apartment is a room that can either be used as an office or bedroom, depending on the arrangement of furniture that folds into the wall and floor: