i love ideas that create spaces without a footprint. by far, the best example is this martha creation. it's a totally functional, suspended shelf that even creates a wall vignette, but takes up no precious walking room in a space of any size.
another idea i think is pretty smart in theory is this interesting foldout desk from world market, although it's sort of astonishingly ugly when closed. i would have to do something to the outside, otherwise i would end up just leaving it unfolded all the time, which would sort of defeat the purpose. but maybe painting it with a high-gloss paint so it looks laquered would help, and then maybe adding a lightweight framed picture or piece of art would help even more.
although it does take up some floor space, i love the incognito compact office from crate and barrel.
it comes in white, ebony or mocha and looks great as a simple console when closed and extremely efficient and neat when open and functioning as an office. this would look just perfect under the window in my little office area.
incognito image from bumble ink; all other images from linked sites