I want to share with you all my little discovery which I found quite awhile ago. My wife own an iPod nano since it's released. Shortly after, we found that we need a way to charge it while we are out for Honeymoon in Tokyo. Without a computer to charge it using the included USB cable, how can we do so?
After some little research, it's found that we could charge the iPod nano using a Motorola USB charger which we own from the Razr V3! Since it accept inputs of 100V - 240V and outputs 5.0V, 550mA current with a USB Mini-B Male type adapter, that means we could get a power source anywhere in the world which is sufficient for USB charging! What we need is just a suitable USB changer that could fit both ends.
So, I bought a little USB changer of type 'USB Mini-B F / USB-A F' (just cost a few USD), join the Motorola USB charger and iPod nano (pluged with the included USB cable) with the USB changer, and the iPod nano get charged, without using the USB charger from Apple which costs USD 29.00.
Besides, I also managed to charge my Palm Tungsten T3 in the same way with a proper USB adapter for T3.

(USB Mini-B Female adapter end, connecting to Razr V3's charger)

(USB A Female adapter end, connecting to iPod's USB cable)

(Motorola Razr V3's USB charger, with USB Mini-B Male adapter)

(Note the power input and output of the charger)

(Connected and charging! :>)
WARNING: This is just a little discovery I found, I take no responsibility if you try this and your devices get demaged.