My friend David sent me this link to a video on the Transition Town movement. How communities can prepare for a radical decline in energy availability is surely a question that deserves great attention. There are many types of communities, though: not all are constrained to a small geographical region.
Advances in communications technology have been at the core of the transformation of community during the industrial revolution, from the telegraph through radio and telephone to the internet. But long distance communication goes back to ancient times: the famous post office motto is a description of ancient Persian letter carriers by the ancient Greek, Herodotus. It is quite conceivable that our modern person-to-person media of telephones and internet could well collapse as the resources required to maintain their infrastructure become increasingly scarce. A worthy challenge and opportunity is to find a way to use our present infrastructure as a scaffold to reconstruct the more robust system where ideas are exchanged via the physical exchange of ink on paper, via the post office, via snail mail.
There are many reasons to exchange letters and many general types of relationships with the people whom one might write to. The primary sort of exchange relationship is with people one knows primarily face to face. Perhaps a family member has moved away, or perhaps one maintains communication with people one has met while traveling. At the other extreme, one might exchange letters with representatives of various widely known institutions such as departments of the national government.
Between these extremes are networks of people with some common interest. e.g. scientific or artistic. Modern science was born with the rise of published printed journals that could broadcast ideas across large international communities. These journals grew out of networks of exchanged letters, which continued to thrive alongside and as a foundation for the printed journals up until the era of email. A beautiful vestige of this practice is the archive of Edsger Dijkstra.
Another recent technology that may well not long survive the resource peak is the photocopier. Nowadays there is a quite smooth spectrum of printing technologies, tailored for print runs of every size. Simple printing technology is good for large numbers of copies where the large set-up time can be effectively amortized, so that may well continue, as it has, for centuries. The real ferment of fresh thinking doesn't happen at that large scale, though. Vital culture can happen on a limited budget, but only with effective structures in place to make the best use of those resources.
Three practices necessary to an effective percolation of ideas through a network of correspondents are: a distributed set of address books, sufficiently cross-linked; a regular practice of letters being forwarded so that a single letter has multiple readers; and a regular practice of copying letters or extensive parts of them.
Keeping track of the locations of people has some challenges. People move from place to place at various time scales and it is not efficient to broadcast each move to every possible correspondent. There are also safety issues with broadcasting addresses too widely. To send a letter will generally involve several steps of forwarding, each step facilitated by a correspondent incrementally more intimate with the addressee. Some system is needed whereby copied and forwarded letters include enough network tracking data so responses can be sent back to the original author.
In the best of worlds, such a network of ideas being exchanged would already be up and running as internet and telephone systems crumple. Bits and pieces of such older systems still exist, e.g. telephone trees as an earlier form of an email distribution list. While our advanced technologies continue to function, these more primitive and resilient systems will have the form of a Creative Anachronism or some similar entertainment. But, like amateur radio or backyard gardening or bicycling, snail mail networks could very well take over as a core cultural practice, and on an almost unforeseeable time table, as resource constraints make it difficult or impossible to recover from the various inevitable failures of the more advanced technologies. Resilient technologies have failures too, but recovery is less expensive.