My constant companion since age 14 has been my little red Swiss Army Knife. It is the "Tinker" I believe.
I've used it for everything from woodcarving to solo-surgery, cleaning bream to skinning critters up to and including a ~ 200 lb black bear. I can not say enough about this tool.
It is light, sharp, and strong. Mine has two blades, can/bottle openers, two flat and one philips head drivers and an awl. Out of everything, I use the small blade most. That little claw is SHARP!
It is not a multitool in the same sense of the word as a Leatherman or Gerber, as it does not have the pliers, but I find myself carrying it over my Gerber 99.98% of the time.
The Gerber multi-plier is great by the way... Kinda chunky though.