A good pocket knife or multi-tool like a Letherman or Gerber. I always have a pocket knife on me and a multi-tool in my car. Either one gets used pretty much daily.
ha! I definitely should get an ornamental gold one, at this point.
I've used steel for a long time for the durability, but switched to a brass one for my current job. we have important stainless surfaces that need to stay polished and unmarred.
Can't upvote enough. My Leatherman gets used probably more than any tool I own. Anytime I'm fixing something whether it be the house, car, lawn equipment, the Leathermans always useful.