Those who like to sew small, cute things (as opposed to large, ugly things?) might enjoy the zipper card pouch tutorial from Joanne at Craft Passion. My mom just tried it out and here's the result. Adorableness! Mum, did you put your Discover card on top because you knew I'd like the orange ball?
You can store some credit cards or a bit of cash in there.
Or put in some wallet-sized photos of your favorite grandchild to show off to friends and family. If you don't have a grandchild, maybe you have a pet or a houseplant.