It's basically a quilters party on wheels...actually - several quilt stores work together and over a given period of time have prizes and sometimes freebies for anyone who visits their store during the designated period of time. Stores are usually in a given geographic area so that participants can easily drive from one to another in a day. Usually you can get your name entered at each store for prizes from that store and sometimes if you visit all stores and get a stamp from the store you are entered for a grand prize. It's a marketing technique that is a lot of fun for quilters.
and as the other poster reminded me, there is a virtual shop hop on line where you visite several web stores.