There was a thread a few days ago about donating to Habitat for Humanity in the wake of Hurricane Katrina. Sorry I missed posting to it before it was archived, but I wanted to say that I know all of the affiliates in the greater New Orleans area very, very well through past organizational relationships, and there is no one I would trust more with my time and resources than those who lead New Orleans Area HFH, East St. Tammany HFH, HFH St. Tammany West, Thibodaux Area HFH, HFH of Greater Baton Rouge and other neighboring groups.
You can give through Habitat International, or look up contact info for local affiliates to give directly. Their infrastructure is probably still out for now, but I have no doubt that these Habitat affiliates will be up and running again as soon as humanly possible.
Someone mentioned that they had been turned away because they were not a Christian - I hope you reported that to Habitat International, because it is a serious violation of the spirit and founding principles of the organization. None of the affiliates in southern Louisiana will give you that kind of runaround - of that I am sure!
Here's the old thread:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=104x4632121#4632516