I still think you need to have people on the ground. And lots of them. As a small aside, I work for a Groupon-clone website in a non-US market. I've built a very nice Internet-based redemption interface for the business owners to check the clients' coupons. Guess what? ~75% of them don't even have Internet at the POS, they print their coupon lists at a home computer and somehow manage all the clients we send them manually. We also manually create accounts for about half of them, because, apparently, creating an user account on our Drupal-based website is too damn difficult.
Maybe this time is different, and all the tech-savy small-business owners from out-there will go directly into Google's arms. I personally doubt it.
Big overlay on google maps: "Get 0.5% off your total bill at Joe's Pancake House when you order at least sixteen pancakes!"
PS. Man, I feel like pancakes now
Open up Maps, hit the 'Find Places' button, and pick Restaurants, for example. There's a sponsored, very generic link for Groupon here; Google could do one better by adding a little 'offers available' symbol beside some of the restaurants.