DirectNIC has been my registrar of choice for years; all of my current domains are registered with them, and several of our clients use them as well.
DirectNIC's offices are in the heart of New Orleans, down the street from the Superdome. They have remained online and almost completely operational through Katrina and its aftermath (apart from their free web hosting service, restored today) due to the almost literally heroic efforts of their data center staff.
DirectNIC's Crisis Manager, Michael Barnett, has been updating his blog during the disaster, including photos and a webcam feed.
If you want a reliable hosting company, these folks have certainly proven that they'll do whatever it takes to keep their data center online.