Not to take away from the people in need of support, keep in mind that many had to leave their beloved pets behind, not to mention the suffering of the stray and ownerless animals in the hurricane area. If you would like to make a donation to assist in the humane efforts, you might consider these:
The ASPCA has a Katrina Disater fund to help rebuild animal shelters impacted by the hurricane.
Noah's Wish is an all-volunteer group devoted exclusively to rescuing and sheltering animals during disasters.
And the ever-popular Alley Cat Allies is friend to friendless stray and feral cats.
In addition, I imagine the USHS (US Humane Society) and local SPCAs in Mississippi and Louisiana are responding to the need as well.