Here is N.Z. Bear's Hurricane Katrina: Blog for Relief Weekend page (including a log of participating bloggers). You just want to hug him. And the omniscient Professor, of course, has the big list of recommended charities and resources working to collect funds.
I contribute to Habitat for Humanity because to rebuild lives blown apart by the storm and its aftermath, first and foremost, people need homes.
So do what you can for hurricane katrina relief and flood aid. (We are supposed to put in those links. Not sure why but there they are.)
I am a New Yorker and I remember the outpouring of assistance after 9/11/01.
And like New York, New Orleans and the Gulf states will rise again and prosper.