Groupon doesn't ask you to put your personal reputation on the line to endorse a product. You're essentially asking people to be pitchmen (or -women) for a pro

Groupon doesn't ask you to put your personal reputation on the line to endorse a product. You're essentially asking people to be pitchmen (or -women) for a product -- which involves putting whatever reputation they've built up among their social circles on the line for you -- for a measly $2. This has an entirely different vibe to it than the Groupon model of "Hey, I love this restaurant, sign up for this Groupon with me and we'll get half price!" The "endorsement" here is less obviously for hire, not least because there's a third-party service in play. Overall, what everyone is telling you (here and in the comments on your blog post) is that putting links and/or endorsements on a social networking service is much more than just a fee-for-service proposition; there are other intangible qualities that are important, primary among them what your friends on these social networking services think of you. You want to believe that your friends post links to things because they're good, not because they're getting a discount. In fact I'd argue that one of the main reasons people like social media in the first place is that it's a person-to-person interaction that's not commerical in nature.