Facebook was a very useful tool during the flooding here in Brisbane earlier this year.

We mainly used it for updates from the emergency services. All websites seemed to be very slow due to the heavy additional loads on the servers as everyone tried to get information about flood levels / road closures etc. Facebook seemed unaffected and was running normally, so we could get trustworthy updates straight from the source without having to wait for the normal media outlets to broadcast (and in lots of cases add their spin).

Additionally, many people used it to broadcast help messages. For example, if someone's house was going under and they needed help finding emergency housing for their pets, they would broadcast their predicament and in return offers of help would come back. Special facebook pages were set up for people to post their needs in such a way. So if you have spare space and your house is high on a hill, you can post an offer of help and people can contact you directly.

We also used facebook to 'talk' to friends who were in danger of being flooded and needed to talk to someone to stay calm without blocking up their phone lines.

I don't use Facebook myself for social media but during an emergency its another really valuable communication tool which can also be a boredom / stress saver. A multi use tool :-)