The world is lousy with iPhone cases. They're available in all manner of designs to suite a wide variety of tastes and brand loyalties.
FLIR Systems has a $350 case for the iPhone 5/5S. It's a dual-camera thermal imaging system called FLIR One.
FLIR One is a battery case with two cameras whose lenses are in close proximity. One camera is sensitive to visible light, the other is sensitive to infrared light.When actuated, the two cameras collect images simultaneously. The FLIR One app processes the two images into one "thermograph" The app uses the visible light image to create outlines of hard edge boundaries of objects while the IR image is processed into false colors that fills the frame.
If I had an iPhone 5 or 5S, I'd be shooting the world with one of these things. I eagerly await a FLIR One for iPhone 6.
(FLIR is an acronym! Do you know what it stands for? I'll put the answer in the comments.)