Social media and social networks are often conflated into a single concept, but the reality is that the two are quite separate.
On the one 
hand, social media is a platform (tool) that allows people to connect with one another around common topics. On the other hand, social networks are our social and professional networks, built through our day-to-day interactions with others. The social media platformNextdoor aims to change that. The Wall Street Journal recently ran an article on Nextdoor, which describes how Nextdoor allows individuals to create social networks based on those that live within a given neighborhood. The site has some issues identifying neighborhoods, and with mapping, but in practice it allows individuals to create social networks based on those that live near you. I can imagine this could be quite useful for homeowners associations and the like.