Little known fact: the USB peripheral ports on your computer (the cables going to printers, cameras, etc.) carry low-volt electrical power. This means you can use the big battery in your lap as a big recharger for a gadget. Globetrotting road-warriors have discovered they can carry one less adapter/recharger by packing this small cable. Plug one end into the USB port and the other into the cell phone. As long as you have power in your laptop, you can recharge your phone.
[If you can recommend a good, reliable alternative to this device, which is not currently available, please let us know in the comments below or via the submit page -- SL]