http://techcrunch.com/2013/09/26/mobile-deal-finding-app-shopular-raises-6-4-million-series-a-from-sequoia/

When you go into a mall, it gives you allcoupons around you

http://www.journaldunet.com/ebusiness/publicite/criteo-acquisition-tedemis-1113.shtml

Why not create a system like tedemis but in the real world ?

When someone enters into a shop, you send him a targeted mail after his visit.