I recently read an article by Kiplinger about 8 things to never keep in your wallet. If you follow their advice, you will not only have less to carry everywhere, but you will also have less to worry about if it gets stolen.
How about all those store loyalty cards and cards from restaurants for free meals after you buy a certain amount? I know someone who keeps their loyalty cards, coupons, etc. in a separate wallet in the glove compartment of their car. They keep their wallets that they carry with them very thin with only the absolute necessities like one credit card, driver's license, and some cash. The rest of the cards are easily accessed from the car when they go shopping or out to eat.