If you travel a lot or just in the market for a good USB charger, the Arctic Cooling C2 Universal USB charger would be a great choice.  The 4 input adapters make changing input voltages a breeze.  The 4 USB output ports are 5v and rate varies from 500mA to 2000mA depending on which port you use.  The charging rates are on the side of main unit making it easy to choose which port you want. . .