This is so very cool: Andy Rawson has built a thermal imager that allows you to point your camera anywhere and get an instant temperature reading of your environment. It's available for the iPhone, with an Android version on the way.
The unit and accompanying application overlays 64 different temperature zones on your camera view in real time. The effect is not only useful -- it has a cool 8-bit look too. He created this solution to detect heat escape points in his old house because he couldn't afford a professional thermal detector camera.
The best part is that he's making his thermal imager open source. If you want one, it would only cost you $US150 to make it, which is peanuts compared to professional equipment. [Instructables via Rob Hopeless via Engadget via Petapixel]