This is so very cool: Andy Rawson has built a thermal imager for iPhone—and the Android version is coming soon too. It allows you to point your camera anywhere and have an instant temperature reading of your environment.
The unit and accompanying application overlays 64 different temperature zones on your camera view in real time. The effect is not only useful but 8-bit cool too. He created this solution to detect heat escape points in his old house because he couldn't afford the $2000 to $10,000 price tag of a professional thermal detector camera.
The best thing: he's making his thermal imager open-source. If you want one, it would only cost you $150 to make it, which is peanuts compared to professional equipment. [Instructables via Rob Hopeless via Engadget via Petapixel]