RoomScan is an app for iOS which draws floor plans in minutes - touching your device to a wall is the only input required. Using the iPhone's internal sensors, RoomScan recognises a sequence of flat vertical surfaces, measuring the distance in between and creating impressively accurate plans. When you come to a door, you just tap the phone to the door frame and continue. Claiming that measurements are accurate to the nearest 10cm (or 6 inches), this app - the basic features of which are available for free - is not only great fun to play with, but also considerably useful in every day situations.
The app allows for even more accurate measurements when combined with a laser measure, offering the ability to input your secondary measurements to create a "perfect" plan. You can then export the drawing as either a PDF or DXF for AutoCAD or SketchUp. The technology behind it has a patent pending.