We spotted the clever Tetra in Paris several years ago. It's designed like a piece of origami, with four surfaces that pull out in spiralling levels to create greater square footage, or push in to contract the whole kit and kaboodle into a neat little square.
DWR's Rotor Coffee Table works on a similar principle, but its pull-outs extend all the way down to the floor, rendering the bottom-most layers useless for floor-seated dining or a group game of scrabble. The two are very close in price: Tetra is $1476, Rotor is $1498.
Tetra comes in beech with blue/beige laminate, Iroko with black/beige laminate, and in Iroko wenge-stained wood with white/beige laminate.
Edited from a post that originally appeared 5.09.06