I always carry tea in my bags when going out for more than a day. Black leaf tea, I'm quite addicted to it and having none for a whole day often gives me headache, guess due to blood pressure drop(?).
Let's see what else I carry in never-emptied pockets of my backpack (which is basically closest to a BOB for me, I just fill the main compartment with stuff I currently need and have no worries about stuff like firemaking, cordage, first aid and such, because that's in the pockets already). Cordage - always have a bunch of rdry awhide straps, mostly leftovers from some of my reenactment products. Just soak them for a while and they're ready to use. In extra need, I can always cook glue of them and they could be even chopped fine, boiled and eaten in total emergency. What else...not sure if I've mentioned it already, but I carry a Mosin-Nagant metal oil flask. These are very cheap and easy to find in gunshops and such. I cleaned mine very well and filled it woth molten tallow. Now I can scrape some out with a stick, or shortly heat the flask in ashes or aside fire and pour the tallow out. Takes care of leather, gun, metal and wood protection, as well as dry lips, sore heels, burns and such. Is edible, so I can use ot for cooking and frying, as well as lighting...lots of uses for such a small and cheap thing. Got the idea from Dave Canterbury. What else to mention from the less usual items ...perhaps a sharpening stone and a small file, hacksaw blade (or a a half of it), small roll of binding wire...