Yesterday afternoon, post workshop, I went with my brother across the river to visit the Walker Art Center. Among the major works -- the Chuck Close potraits, the Warhols -- was a fun interface to information about the museum's works: the dialog table. This interface consists of museum objects, and avatars for various "Locate", "Describe", etc operations on the objects. These elements are dragged to each other to execute operations.
How are elements selected and translated? This is the fun part. The user stands holding her hand over the dialog table, with illumination from above. The shadow of her hand on the dialog table screen, and its gestures, are captured and processed. A pinching motion creates a hotspot for object selection, and the selected object can be translated with a dragging gesture. Once you get the hang of it, it's quite natural and fun.