The SimProj Project provides a Processing-based (and therefore Java-based) application that provides a GUI for the simulated calculation of a video projection setup. SimProj allows to add and manipulate virtual projectors, mirrors and projection planes in order to show how the projection is mirrored and which sizes, angles and positions the setup components require. SimProj can be configured to comfortably show all necessary measures that can be ‘easily’ (everyone who has ever built a rear-projection setup knows what ‘easily’ means in that context) transferred to the hardware setup.
That blew my mind. Another great project by Microsoft Research. Also read the paper.
I still love the interaction between real documents and touch interfaces.