I actually found a purse with little card pockets under the front flap so it doubles as my purse/wallet. I like things as simplified as possible.

I just keep the basics in it. Driver's license, my 1 credit card, PetCo Pals card, car insurance card, checkbook, pen, list if I'm getting groceries, cash if I have any. I generally keep my car keys in my pocket.

That's about it.