Maplin have done these for years
http://www.maplin.co.uk/Module.aspx?ModuleNo=99487
Hooking your laptop into your car’s battery for a little on-the-road juice isn’t the safest of options. So battery business Duracell and IT peripherals firm Belkin have launched competing in-car USB chargers. Duracell_USB_charger Duracell's USB Charger glows blue when ready Duracell’s USB Charger is described as one of the …