Lighters don't seem to get much discussion here but to me, it seems like a no brainer. Perhaps that's why it's not discussed, the whole common knowledge thing. There's literally billions of them out there and they readily available, but in a SHTF situation, for how long? Arguably one of the best survival tools available and everyone should probably have a few around. I am a smoker (yeah, yeah, I know) so I always have one on me but a few of my non-smoker friends carry them as well. You never know when a pretty lady will ask for a light. But anyway...
They are cheap, lightweight, and have a long shelf life. Most importantly, they are a fire starter. They also work for light, opening beer bottles and endless other uses. I prefer Bics, reliable and practically indestructible. It's probably a good idea to have a Zippo as well. They run on many different fuels but you need back up flints, etc. For roughly a buck for a Bic it's hard to go wrong. Seems like must for every BOB, maybe could be a good barter item too. Next time your in Sams or wherever, might not be a bad idea to pick up a few.