Here’s an oldie-but-goodie from 2004: Kar-Han Tan, James Kobler, Rogerio S. Feris, Paul Dietz, and Ramesh Raskar, then of the Mitsubishi Electric Research Laboratory (MERL), produced a custom digital camera and software that derives line drawings of a scene, or an object, by analyzing the shadows in four otherwise-identical pictures that are illuminated from different quadrants. The MERL has a technical report from 2005 describing potential medical applications of the technology, and has a good general overview of the process. Raskar has since gone on to the MIT media lab (so you know he’s doing something right), and his page there includes more up-to-date work on the technology.

Thanks to Jon Wolfe for bringing this to my attention.