Strong reason to connect

One of the key concepts in the amazingly cool book Groundswell is the idea of a deep need to connect being a driving force for the creation of on-line communities. Not unlike cancer patients, Harley riders or new Mothers, there has to be a reason apartment residents would want to connect.

What is it that deeply connects apartment dwellers? What is that emotional connection that brings them together? What is the central reason they would want/need/feel/desire/think they should/could/would connect? Deeply? Is there a central reason? Do they even want to.