I have an old version of a usb light that I take on business trips. I don't really use it much for the keys since the laptop screen backlight usually throws enough light for me to type well (sort of touch typing).

I do use it in the hotel as a night light / just in case light. I hate waking up in strange places and trying to remember where everything is. Once stayed in a hotel that lost power and the room was pitch dark. The usb light, running on the laptop battery, made it a lot easier for me to orient myself and let me gather my stuff without running down my edc light.

-Eric