Community Networks and Websites?
The area in which I live (Cairns, Queensland, Australia) has a rather large community of folks that are online and they all usually congregate on an IRC channel devoted to the Cairns area to chat to each other.
They are mostly teenagers but a few older folks also participate. There are also websites for the channel which say where the parties and events in the area are happening and pictures of those parties.
Its amazing how many people i meet in "real life" that also chat on the channel.
Quite a few slashdot readers are there too :)