Forgive me for such an expansive question, but this gets at the heart of my dilemma: optimizing an affiliate program for walk-in retail spaces. I am looking for ways to show our affiliate program is working to our partners. Affiliate programs are pretty straight forward in cyberspace. You can easily map out how traffic is driven to a site where a purchase is made. Validating parking is one sure fire way, so our parking garage partners are happy. But how is this done in the real world so that our restaurants and retail locations know we are working to connect each other? Especially when customers do not always mention how they arrived at your location.