In the same vein [ugh, sorry, pun not intended] there's the video magnification techniques that detect and amplify micro variations across video frames - e.g. in skin tone/colouration for pulse monitoring [1] and e.g. in structures for engineering analysis [2].
Measuring the human pulse from tiny head movements to help diagnose cardiac disease [1]
[1] http://www.kurzweilai.net/measuring-the-human-pulse-from-tin...