Since a wallet was mentioned...
I'll add that I forgo most of the stuff usually in a wallet I take only drivers license, health insurance card, debit card, credit card, and a little cash. That all fits one of those little credit card envelopes, a similar sized ziploc bag, or a credit card sized duct tape wallet. If I travel outside the US, of course I'd add a passport. That all stays in my handlebar bag or my little backpack.
Most of the things that are typically in my pockets around home stay home. I am kind of surprised when I see folks on tour with a big fat wallet and a big bundle of keys. If I need to take a car or house key (either, generally not both) it is on the cord around my neck along with my ID "dog tag".