that the majority of mobile phones, mp3 players etc can't all use the same charger that puts out 5v and uses the same plug as one of those small usb connectors? This would have many advantages such as only needing one car charger, being able to charge off a PC and reducing cables as a lot of devices come with usb cables anyway. The other advantage is of course that chargers would be interchangable and easier to replace. It could also be good for the environment as the chargers could possibly be sold seperately. Is there any reason this hasn't happened?