The Green Plug uses the USB ports common on small gadgets such as MP3 players. For bigger items, like laptops, it has proposed a modified USB connection with extra wires that delivers more power. The company says it has signed on manufacturers that, early next year, will sell gadgets such as monitors and digital picture frames with traditional chargers and the Green Plug software. A five-port charging hub will sell for about $100, with possible rebates from utilities.
