I usually carry a knife and a lighter. I don't smoke, but I used to carry it to activate the bit of shrink tube used with the braided loops.

Since I've gotten away from those, I still carry it (and the knife), as a very abbreviated survival kit. No, I dont expect to ever need them, but who really expects the events that lead to survival situations? I figure the 2 hardest things to provide for myself in the woods are fire and a cutting implement. The lighter makes fire about as easy as you can get it without packing in firestarter logs, and the knife, a heavy, high-quality style is useful for a wide variety of purposes, from cutting wood to cleaning game, to using the serrated part to saw at branches.

I also usually have a bag of sunflower seeds, and, on a full day trip a bottle of water and a bottle of...something else more potent.