DTNs (delay tolerant networks) have been studied to death in academia sigh. I'm a bit jaded by this line of work. People keep talking about how useful this would be in the case of disasters. How the heck will we recharge all our batteries?

The most reasonable solution I've seen for diaster communication is that implemented by the folks in Berkeley (and I'm sure adjoining towns as well .. don't recall details). They have (or are planning to) have sheds spread around the town that have HAM radios, manuals for emergency situation handling, even some fuel. The idea is that if a disaster occurs (i.e. the Big One), people in a neighbourhood can communicate with others via these sheds. I saw a prototype of this at an Intel Research Berkeley (RIP) open house a few years back. Now that was a decent idea!