Greg Tseng's answer to Next Big Things: What will be the next big idea after social networks, and why? - Quora
Over a billion people use social networks to stay connected with friends but where do you meet new people and make new friends? With social discovery services, I believe we will finally fulfill the Internet's original promise to connect people regardless of physical proximity. There are now 2 billion people online, 5 billion including mobile, that are all a few clicks/taps away and I believe most human relationships in the future will first form online.
Social networking is a comparatively easier relevance problem since you're simply connecting to people you already know, out of the billions out there. But social discovery services need great algorithms to figure out which 50-100 out of billions to introduce to you. That is a much tougher problem but I believe will be solved and forever change the way human relationships are formed.