I have a few things I can add to the list just for fun:

Razor blades.
Mirrors.
Eye wear, especially reading glasses because in the post-apoco-clypse-zombie scenario, Optometrists will be among the first to go.
Religious items (non specific if barter is on your mind).
Insect and zombie repellents.
Padlocks.
Several flags of your country or otherwise (moral booster and can aid in gaining assistance).
Condoms and other forms of birth control at least equal to amount of rounds you stockpile. <laughs>
Fabrics by the yard or meter.
Small plastic pencil sharpeners.
Plastic hair combs.
Chalk. It writes on a wider variety of surfaces than pen and pencil.
Chicken wire and mesh window screening.
Bleach.
Small trowels for digging cat holes, gardening, etc.
Some of those hand held wind up style small electronics chargers w/adapters of different sizes.
25,000 Doug Ritter Pocket Survival Paks (in case you lose one)