Thermal cameras are expensive, which is why they're mostly used by firefighters, contractors and psychotic aliens. Fortunately, that's all about to change thanks to the FLIR One, which is an iPhone case with a tiny thermal camera stuck on the back. All you have to do is strap your iPhone 5 or 5s into the dock and, once you've downloaded the app, you're ready to go. Using multi-spectral dynamic imaging, it can create hybrid images, adding extra detail to the thermal pictures, or plain-ol' thermal pictures in the dark. When you point it at a subject, the FLIR will also give you a temperature reading of what you're pointing the device at.