I plan on definitely stockpiling more water.
Though some people were unable to leave (sick, elderly, no transportation, etc.), a good number of people evacuated New Orleans and the surrounding areas before the storm hit.
The more and more I see about the hurricane and its destruction, the more I think I'd probably hit the road. Not just because of Mother Nature herself, but also the unpredictable chaos afterwards.
Katrina has been a swift kick-in-the-butt reminder to finally get my important paperwork and documents together, and waterproofed.