I've had my head in the sand these past two days, and barely know what's going on down in New Orleans and Mississippi beyond the bare details, but... on the slight off-chance you haven't seen this elsewhere, Glenn Reynolds has a master list
of charities and relief agencies that are helping the victims of Katrina, if you'd like to donate.
As a side note, I've been told before that, when giving to an organization like the American Red Cross
, it's usually better to make the donation out to, say, their general "National Disaster Relief Fund" rather than the "Hurricane 2005 Relief," simply because ARC is required to spend the latter money entirely on hurricanes, and if they get an overflow of donations for Katrina—as seems possible—they can't go and use the surplus for other, lesser-noticed disasters. Usually these organizations know best where and how to spend their funds, so I prefer to give them the flexibility, although it's a minor point: obviously any sort of donation helps a great deal.