Also great for website or application developers, to take a screenshot of their stuff working on the iPhone. Especially website developers, who would otherwise need to install the software development kit to take a screenshot, which can be a pain in the ass.
If anyone is reading this and wondering how you take a screenshot, hold the home button down, and then immediately press the sleep/wake button on the top. The screen will flash, and the image will be saved to your camera reel in Photos.