In 2008 Dropbox was in private beta. Drew Houston had a problem every founder knows: the idea was hard to explain, and the product was hard to show.
So he made a short demo video for the beta launch and posted it to Digg, a popular link-sharing site, with in-jokes written for that exact audience. It showed what Dropbox would do for someone's day in a way a feature list never could.
The beta waitlist went from about 5,000 people to 75,000 in a single day. The team had been expecting 15,000, at most. Rather than let everyone in at once, Dropbox opened the doors gradually, invite by invite.
The takeaway for founders
The story of how your product changes someone's day can be more convincing than the product itself. Tell it early, and tell it to one specific audience.