Maybe we can harness the power of the web to help address the pesky problem of businesses that leave their doors wide open during summer. Someone needs to write an iPod/iTouch application to run when they see the problem, and then show the output to the store manager. The inputs to the application would be some basic measurements, such as an estimate of the width and height of the doorway, and the outdoor temperature. With that, and some basic heat transfer and cost assumptions (e.g., $0.10 cents per kilowatt-hour), the application could provide a read-out of how much money per day is being wasted.