I recently had something VERY similar. I billed it as a 'Woot for Mobile Apps'. You give me your email address, I send you a daily email with a highly discoun

I recently had something VERY similar. I billed it as a 'Woot for Mobile Apps'. You give me your email address, I send you a daily email with a highly discounted app or an app that is free. It's probably not anything that couldn't have been overcome with a massive marketing effort, or with a sizeable marketing budget, but after split-testing a variety of slogans, taglines etc., our cost-per-acquisition proved to be too high to be sustainable, so we shuttered the service. My guess is that the acquisition cost goes down after you've reached a tipping point, but we weren't able to identify when that might be, and the acquisition rate was slow enough that we didn't deem it feasible enough to pursue. Good luck though.