If you are going to live with less stuff, it's nice if it serves multiple functions. Here is an interesting looking desk from French designer Florian Jouy that turns into a bed.
Trouble is, when unfolded the bed is so close to the floor (and as hard as the floor) that there is probably not much point. And if the three cushions are soft enough to sleep on, then when stacked up three high they will be impossible to sit on.
Not quite there yet....via The Design Blog
Other not so successful desks into beds:
Transformer Furniture: Quickie by Jared Dickey