(via @blprnt)
Today I stumbled upon a quite nice interaction technique that The Office for Creative Research developed for their Specimen Box project (in conjunction with Microsoft's Digital Crimes Unit). Their 'cleaving' lets people split the visualization into two with a simple two-handed gesture. This, of course, works especially well on a nice large digital display:
The whole project is chock-full of interesting touch-based interactions, so check out all videos about Specimen Box.