The Picture Wall Company offers a template for arranging and hanging pictures without the sweat and tears involved in the traditional trial-and-error method.
Their "Perfect Picture Wall" is a one-sheet template that is level to the ground, adheres to the wall and directs you where to hammer in the nails. No measurement whatsoever is required; just fill and hang the frames. The set includes everything you need except the hammer.
Plug any device to the Kill A Watt to find out how efficient or inefficient your home appliances are. The LCD screen will display energy consumption by kilowatt-hour and will forecast costs so you can figure out the device's electricity expenses by the hour, day, week, or year. Costs about $40