Something light hearted. I purchased, some time ago, a small Li-Ion battery for external power for my laptop and other devices. These batteries are great, getting down near $100, weighing very little and, with 110 watt-hours, able to keep a laptop going all day at a conference or over most of a transoceanic flight.

This particular battery, made in China, contains one of the more amusing bad-english warnings on the label, though, particularly item #3.