It's not a bad idea to measure a room before you go out and buy new furniture. And if you've got an iPhone, that becomes less of an ordeal because you can trade your tape measure for this slick app called RoomScan. It automatically generates floorplans by simply tapping your phone on every wall.
Presumably relying on your phone's built-in GPS and gyroscope to determine distances and the orientation of walls, RoomScan is accurate to within about half a foot. If you're roughing out a floorplan, that should be adequate enough. But if it's not, you can opt for the £2.99 'pro' version that lets you specify exact distances (if you have a separate laser measure) and easily place doors and windows. Now if only there was an app that automatically moved furniture too. [RoomScan (iTunes App Store) via SlashGear]