Ideas
Here are some ideas for you.
My most actively used item:
Electrical Tape. In particular Scotch 33+. I must have at least 4 rolls in my truck. One in my hunting bag, a dozen around the house. This is probably the quickest and most versatile item to have.
Altoids Tin: An altoids tin works greate for an easy to grab "I don't know what kind of adventure I'm getting into but this will at least cover the basics".
Contents
$50 (I've used this the most, in particular when I forget my wallet. It used to be $20 inside, but then i had an experience where I forgot my wallet one day and had filled my gas tank. $20 doesn't buy much gas these days so I upped it to $50)
A blank Check- Like the $50 it can cover for larger expenses sometimes
A mini bic lighter - I see a lot of people talking about flints and such. Makes sense as a last resort, but lighters are a lot easier.
Waterproof matches - backup to the lighter
A leatherman micro tool - very minimum to do some light cutting and such
A single AAA flashlight. I'm a fan of the Fenix LD02. Put a plastic disc over one end of the battery so it doesnt discharge errantly
A compass - Just a micro size cheapo compass
Some drugs - I take a piece of pres-n-seal and place some childrens asprin (in case of heart attack) and some ibuprofin (i use a lot of this). set it on the press and seal sticky side, fold it over and make a little flat patty of it.
A couple cotton balls - Fire starting material
A Ranger band - Actually its just a 3/4 inch wide hunk of a cutoff bike inner tube. this goes around the tin to keep it closed