If people are looking for yet another way to help New Orleans, Direct Relief International -- name notwithstanding -- is offering to "replenish medical inventories or provide emergency medical material". Hopefully they'll be able to get these supplies to wherever the refugees are going, as well as any remaining hospitals/clinics still open in the city.
Only wrinkle: their website, as I write this, doesn't have a way to designate donations for Katrina relief. However, there is a place for comments. Enough comments might spur them to set things up for specific Katrina relief donations.