I've learned about a fair few local services via Groupon and Living Social. They don't work for all products, but for the products they work for, I suspect they're more effective than advertising. I walked RIGHT BY a restaurant near my office twice a day for 8 months, but I finally tried when it was on Living Social's Instant Lunch. There are a few more restaurants where I work (Judiciary Square/Chinatown in DC) like that. It was more effective than if they had put up posters or billboards and way more effective than if they had gone even bigger with their advertising.