When a bunch of people in a neighborhood, either houses or apartment buildings start stringing EtherNet together and setting up internal sites or access to the InterNet. 

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You get this "for free" on a cable modem network, except you're not supposed to look at your peer nodes. Except there is always someone there sniffing your packets.

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Ah, but in a true CommunityNetwork, you're not paying for InterNet access unless you want it.