myself, i tend to have a pocket knife at all times. i have 2 sets of keys that i'll use, one larger and the other smaller. on the small set, it's just keys. on my larger set, a can opener tool similar to ones used in ww2, a spark plug gapper, and a gerber multi tool that's great for popping paint cans/beer and using as a screw driver. in my wallet i have a little metal card tool that's good for emergency needs when i don't have a socket wrench. though i don't smoke, i often have a lighter too.