There are some local groups building "open" internets over W-LAN and hacked Linksys WRT54G Routers running Linux.
So called "Freifunk" Initiative.
Hardware runs on 12V straight and is tough and there is a ton of modifications (from extreme hardware overhauls to simple toilet-paper-roll-range extenders) and can cover quite some distance out in the open.
They can be bridged, switched, .... and the hardware is ap. 50 bucks.http://www.amazon.de/Linksys-WRT54GL-DE-Wireless-G-Broadband-Router/dp/B000EHIA06
Basically everybody with an device that has W-LAN can join the group, the routers last long on any car battery and some energy saving NetBook could actually provide the basic entry point and run some basic mail, file and text-services.
You can add DNS servers, proxies according to your wishes our run the network private based on allowed MAC-adresses.
I would consider such a basic network in the local area a mayor boost to morale in an crisis !