I have a fanny pack with a portable GPS, screwdriver, 6" needle nose vicegrips, leatherman, a big red 4 tip screwdriver that doubles as a canopy breaker, matches, 2 AA batteries for the GPS, zip ties, pen, business cards for a bread crumb trail, and a sharpie for signing autographs at airshows.
I always carry a couple water bottles and some GORP on long X/C trips.
Most of my stuff is more about surviving in flight than on the ground. A vice grip is one of the most useful tools you can have in an airplane. clamp it on a broken anything and you have a knob or a lever. you can fix a fuel selector, rudder cable, i could grap the mixture or throttle cable below the quadrant if need be.
I know a guy who broke the gear handle on a P-51, grabbed his vice grip and put the gear down. He had it gold plated and put it on his office wall.
I should probably make an "on the ground survival pack" as well.
Tailwinds,
Doug Rozendaal