ORIGINAL: Stainless
All my hunting is done on public lands so I get a lot of leg work. I couldn't compile it all together with out my gps. That is my best tool.
I agree with Stainless, other than my bow/muzzleloader, my GPS is with me on every trip....hunting or scouting. Prior to the gps, I would pass a tree or general area and try to make a mental note. Those mental notes get deleted over time.