The reality is if we lose 'instant contact' with one-another then we have no real way to warn, or cooperate with others due to the impending threat, perhaps related to the fall of the net.

Wifi and bluetooth are a great way to rig up networking, locally. Using radio like CB or HAM we can transmit data packets in a way akin to dial-up. We could use this method to link the networks, if there was a coordinated effort. I rather enjoy simple command line interactions. It feels more personal for some reason. Hehehe, and it's great for the Matrix fan in all of us. I'm currently working on getting a BBS type system running on my android phone and I can broadcast a wifi AP for a decent distance. Perhaps this method could be used.

If the net is down because of electricity issues then it's a whole other ballgame, however.