Microsoft SecondLight multi-touch device shown off

It takes the tabletop, multi-touch display concept and adds the ability to project images into the air thanks to a liquid crystal screen timed to be transparent on alternate frames, enabling a projector below to beam an image right through it. Your eye doesn't notice unless you hold something opaque up to scatter the light (like tracing paper, for instance), meaning the device can show a picture of the night sky on the surface while highlighting the constellations on paper. The must-see video below shows how the thing can also track objects above the glass, turning a sheet held aloft into a second multi-touch display.