What forms of communication have been used during recent disasters e.g Hurricane Katrina, the Asia Tsunami?

Various forms of communication were used in recent natural disasters such as Hurricane Katrina and the devastating 2004 Indian Ocean Tsunami.
People communicated with the affected people through the internet, online communication programs such as Skype and Facebook, telephones, and the media.

Through these forms of communication people were saved, though, lots of people died.