I wouldn't blame anybody for looking down on smartphones if they are so inclined. Certainly it is better, wherever possible, to use tools which do not require electricity.

But smartphones are incredibly useful on account of built in gps, map software that doesn't need connectivity, etc. If you're going to have one thing, besides lights, that needs electricity it should be a smartphone.

This thread is for suggesting apps that you've personally found useful while /out/. For example, I frequently use BackCountry Navigator.