Lately there's a lot of hype surrounding "group buying purchases" such as Groupon, LivingSocial and many more. I'm sure there some of you guys in the community would like to build the same, at least a site that provides similar functionality and features on how group buying sites operate.
First, I think we need a payment gateway system to it. And then, self service sign-ups for businesses, daily newsletters.
Please shed some light on this topic and what modules you think are appropriate to develop one.