Find one person who needs this like they need oxygen. Ask them to tell their friends. Bonus points if they have a higher than average profile / fan base / etc

Find one person who needs this like they need oxygen. Ask them to tell their friends. Bonus points if they have a higher than average profile / fan base / etc at the moment. Repeat. If you cannot find one person who needs this like they need oxygen, it is highly likely that it is (regrettably) not the case that many people would enjoy this if they just knew about it. This suggests a simple and effective criteria for building products in the future, because you don't need to have the website actually coded to extract signal on "Do you need this like you need oxygen?" from people. (Instagram/Vine pass this test in spades: while you could pick many, many potential use-cases, "Hey 14 year old popular girl, would you like to get constant public positive feedback from weakly attached friends?")