Just brainstorming here but.....
A couple of 'biners
1) holds things on to your belt, pack, keychain
2) Improvised toggle to replace button (A little large but better than dropping trou.... <img src="images/graemlins/wink.gif" alt="" />
3) compined could make a compound pully arrangement to increase your pulling power
A couple - 4 nails + improvised hammer / multitool, stone, brick, handy piece of metal from wreck of downed plane you are climbing out of etc.
1) attachment point for biners used as #3 above
2) Steady / reinforce damaged structures
3) Pot-stand for small stove
4) leather awl
5) Attachment point for snare wire
6) point for spear (hunting and self-defense)
7) Chisel for wood working in shelter building
8) Nail for shelter building.
9) pin replacement for grenade <img src="images/graemlins/shocked.gif" alt="" />