Augmented reality apps are steadily increasing in complexity, letting users do more and more with the cameras in their devices. One such app is the new app MagicPlan, developed by Sensopia. What MagicPlan does is that it lets you create floor plans for homes simply by using your camera in your iPhone 4 or iPod touch 4th Generation. While the iPad 2 isn't mentioned, the app would presumably work with it as its cameras are 720p, just as the other 2 devices, which is likely why the iPhone 3GS is not supported.
While I recommend watching the tutorial videos the app provides to figure out how the app works and how you are supposed to use it, you basically are supposed to stand in the center of a room, and aim at the floor corners of a room, lining up the 3-dimensional corner lines with the actual corener lines. You go around the room, taking a picture of each corner, including door positions, until you get back to the first corner of the room. This creates a floor plan for the room, which you can then edit to correct any errors that may have popped up through the photography process. You do this for every room of your property until you've created a complete floor plan. There are plenty of options for a variety of rooms and specific door types to make as accurate a floor plan as possible.
The app is free to download, and it gives you a watermarked JPG, PDF, or web published version of the floor plan when you're done for free. For $4.99, you can remove the watermark, and can pay $9.99 to have the file hosted on the web for 6 months by Sensopia, so other people can view your floor plan directly on the web - this is useful for people who would want to show off a floor plan to potentially interested buyers. This app is a unique use of augmented reality to try and bring some definite utility to augmented reality apps, which have otherwise been used to enhance location-based searches, and for gaming. This could also potentially make an otherwise difficult task much simpler thanks to the advanced technology we can carry around in our pockets.