Like any mom, I am usually driving with one hand on the wheel and one hand on the floor -- groping for dropped sippy cups, clean tissues, wipes for sticky hands, and my sanity, which appears to have been ground into the floormats with pulverized Cheez-Its.
I finally reined in the chaos with this simple little plastic basket I call my "co-pilot" box. When I don't have an adult passenger to handle the dispensing of wipes and snacks, this is easily within my reach. For immediate back-seat emergencies, I've stocked it with pocket-pack tissues, a full package of wipes and some snacks. Other essentials include a couple of diapers (in a cute bandana pouch a friend gave me), reams of Purell wipes, a bib and diversionary items like crayons, stickers and small board books. My cell phone and sunglasses sometimes sit here, too.
This tote is from the Container Store. It has turned out to be useful to have a handle for lifting and stashing it when I have a real co-pilot along for the ride.