Carnival of Hurricane Katrina ReliefInstapundit's list of hurricane relief is duly posted here.
My advice is to give money, and lots of it, to the charity of your choice. They know what they need, and right at this moment they probably don't need many warm body volunteers. The time for in-kind donations and work camp church expeditions will come later.
Coincidentally, I have some photos from relief efforts from south Georgia's 1994 floods. I'll post some of those once I excavate them from my cartons of pics.