OK, this is going to be one of the odder uses of my PDA. But it is still one that I think valuable.
A few years ago, we had a violent evening storm. It came upon us rather unexpectedly, and the lightning knocked the power out. My very young child became scared at the noise outside, and I knew I needed to get to the emergency supplies for the battery-powered lantern and flashlights. The problem was it was pitch dark, we were not in the room where the supplies are kept, and as I stood up to move toward that room, I smacked into a large piece of furniture I had forgotten was there (in my defense, we had just moved in…)
So I grabbed my PDA, which happened to be sitting next to me…
When I turned it on, the backlight gave me enough light to light my path and get to the emergency supplies.