A few credit cards (used to carry only two, but when one got swallowed by an atm in a foreign country I learned better), a debit card, id card, drivers license, medical insurance card, car key card, bills, coins. Sometimes a few receipts to expense or the odd parking card.

Basically everything is a backup, my phone has all my credit and debit cards and my car key, but I still carry the wallet just in case: phone dead, traffic stop, sick, etc.