Wow, what a great thread this has proved to be, thanks to the OP for making us all put on our thinking caps. My Christmas afternoon has been enriched by all you folks.
My most useless item would be the kitchen sink. I carry everything PLUS the kitchen sink it seems! My peers think of me as the go-to guy when anyone needs something as I often have it; moleskin, adhesive & duck tapes, eye-wash, & on & on. That being said my outdoors mostly revolves around the water either in Maine or Florida, in canoes or kayaks. This makes weight nearly a non-issue, volume however is my adversary.
Mrs. Maineboatman, asked while preparing the Christmas dinner, immediately said matches; useless unless the situation is absurdly perfect. Wet, windy, cold fingers & such make them non-fire starters. Once you get the fire going you wont move on in an emergency, you will find & drag wood to the fire, letting it burn its own lengths into pieces for you. Always thinking! Its clear why Im a lucky man indeed!
I want to address two issues here which I consider very important. Get rid of the lashing holes on all your knives. Do not make a spear etc. because you will break or lose your knife. Make the spear, gig, snare using the knife. Keep the knife safe at all times. I truly carry more than one knife on all trips (as well as a little bag ax from a forum member here, stephen5, Stephen Osborne in Canada. His "Little Bag Axe" about $150 is a MOST excellent item!).
Fishing kit; here I surely think far too much of me but here goes. Hooks & mono line, plus braided (the new stuff like Power Pro etc.) are fine. I too carry them. I also carry a mesh paint can strainer to make a dip net from. Minnows & SMALL fish of 4 inches or so are the easiest to capture and to make a broth of the whole fish, no discards as the nutrition winds up in the soup. Bigger fish will leave you hungry mostly; learn how to make bush hooks to continue food foraging. Small hooks & 6 8 pound mono for small fish fairly quickly, larger hooks with 20 60 pound mono for bush hooking catfish & such. Also think of a weir made from brush latticed to small openings & staked into the river, stream or shorelines. Drive small fish into the weir for your dip net on a six foot pole fashioned with the knife you didnt lose stabbing into the water.
Keep the thoughts coming fellow BF folks, the adaptable mind will find a way to survive. I have already taken note of several good ideas in this thread & while my area of knowledge is very limited in my experience I hope I have prompted thought.
Maineboatman
maineboatman@cox.net