2 things I'm always going to have either in a pocket or a HPG bag where I can get to them easily:

A ziploc bag with TP in it
A ziploc bag with glucose tablets in it

Neither of those things handle rain or a sweaty pocket well, thus the ziploc. Thinking about it, ziploc bags may the most heavily used non-hunting item that I always have with me when I'm hunting. I use them for so much.