As we've begun to share definitions within our office, we've found it a challenge to have more than one person interact physically with a definition and thought maybe we just need more space.  We're using a rear projection piece of glass as our Grasshopper canvas and the Rhino environment projected on the wall.  That alone is great but it also looks like multi touch could have a promising future in Grasshopper.

Follow the link for more info:
http://lmnts.lmnarchitects.com/interaction/ghcanvas-real-estate/