If you’ve got cash to spare (I know, but this is serious), that button on the left takes you to the American Red Cross donation form. Cash is by far the best thing to give in this kind of disaster; clothing and canned goods can more easily be purchased on scene and cash has the added benefit of supporting the local economy.
The way things look at this hour (1900hst/0100edt) New Orleans and its surrounding areas are gonna need an awful lot of help. Later advisories will be posted at the National Hurricane Center site here.
Update: The Nielsen Haydens have a bunch of useful links posted here.