Building Communities with Software is an old article of Joel ‘on Software’ Spolsky’s that deals with social ‘third places‘:

The social scientist Ray Oldenburg talks about how humans need a third place, besides work and home, to meet with friends, have a beer, discuss the events of the day, and enjoy some human interaction.

These were the independent coffee shops and the quiet, smoky bars of the nineties. Now we have online social networks. Joel’s primary axiom of developing a thriving online community:

Small software implementation details result in big differences in the way the community develops, behaves, and feels.