Here's a different twist to the calling card angle. Make sure you also write down the voicemail access number for your cellular service so that other people can leave you messages and you can listen to them from a pay phone. I haven't actually tried this in an emergency situation where the cell phone system could be overloaded, so not sure how reliable it is during an actual emergency. But eventually, even if particular cells are still down, the core system will be able to respond and hopefully people can call your cell number and leave you messages.

After Katrina, so many families and friends were split up and spread to the four corners of the country, and if a landline was their only phone number back in the hurricane area, they had no way to get in touch with each other once they were moved elsewhere.