Maybe there's some information on your iPhone you want to be able to retrieve later, like flight information, or perhaps you want to share that data with somebody else. Some programs, like Safari, let you email information to others, but many don't.

There is a workaround, though: take a screenshot. If you push the iPhone's Sleep/Wake button (See Image - ) and Home button (See Image - ) simultaneously, the screen will flash to white and a screenshot of whatever you're looking at will appear in your iPhone's Photos app in Camera Roll. The image size is 320 x 480 pixels on the iPhone 3G and 3GS and 640 x 960 pixels on the iPhone 4.

From there you can attach the image to an e-mail message or just save it for future reference.