Go donate here.
To be honest and perhaps slightly contrarian, though, I don't think that donations will be the make-or-break for this. The money won't make a real difference until after this is over, and let's be clear: if the federal and state governments don't provide New Orleans every penny they need before a single cent of private money goes in, they've failed in the one duty of government that everybody agrees on: the security of the citizenry.
That said, the money is going to the Red Cross, and the Red Cross does a lot of good that you don't hear about. This money shouldn't be donated because of this disaster, but because of all the other, smaller disasters that happen all the time.