Free apps

App discovery is a known problem for all developers. Users typically rely on the top-selling app lists in their app store of choice as a guide for what to purchase. That, in turn, fuels sales of the same, already popular apps, making it that much harder for new apps (and developers) to break into these top app lists. And while there are curated app lists and some app search engines, the majority of new buys aren't coming from there.  So where do these new apps that break onto these top lists come from?