There are numerous blogs, websites, and other Internet resources on Hurrican Katrina, so I can only mention a couple. The devastation is unbelievable, and our thoughts are certainly with all the people who are trying to cope with the aftermath, but it underscores how important an understanding of geography and our environment is, as has been pointed out many times in the case of New Orleans. Here are a couple of links to some of the many resources out there, including uses of Google Earth to provide locational information on levee breaches.
ESRI is providing GIS assistance for organizations, with information available at http://www.esri.com/hurricanehelp
Here are a couple of links to uses of Google Earth to map aspects of the disaster
(via The Map Room) http://www.kathryncramer.com/kathryn_cramer/2005/08/new_orleans_lev.html
These are still images of Google Earth output:
And finally, if you’d like to help the Red Cross National Disaster Relief Fund: