There are displaced people (and pets- see Yahoo entry below) out there.
If you might have been in the area, people are worried about you.
The internet has tools to help all concerned....
The American Red Cross is promoting the following...
http://www.familylinks.icrc.org/katrina
Fabulous... and dangerous?...
http://wx.gulfcoastnews.com/katrina/status.aspx
... and...
http://www.publicpeoplelocator.com/
Why do I say "dangerous"? The sites allow users to post phone numbers, etc... not necessarily a good idea? Something like "Safe at Aunt Ida's" will tell your friends a) it is you, b) where you are... without telling the wrong people things you might want to keep private?
Worth support..... and has links to other such...
http://www.createforum.com/phpbb/index.php?mforum=katrinasurvivor
Another, more extensive list of links is at...
http://www.packrat-pro.com/katrina.htm
I have also opened a page where you can contribute to a discussion of what would be the perfect system, in hopes that work will go forward to have it in place for the next time.
The page above was put together hastily to get it out the door. Click here for a similar, improved page with resources for Katrina victims and those who care about them.