One way to experience viscerally the devastation of Katrina is to watch this slideshow over at Flickr of tens of thousands of images collected over the last week and a half. You can adjust the speed in the top right to 1 second per image and minimize the window so it sits in the corner of you screen. After watching this for an hour or so, I think you can get a pretty good sense of the devastation inflected as well as the hardships people are going through.
Here are just a few images I found particularly striking:
Dead Man Watched On By a Dog
Crying Boy in A Shopping Basket
Woman In Curlers Recovering at the Astrodome
Bush Playing Guitar In Front of A Crying Mother
Last Of the Holdouts
Two Families Waiting For Help On a Roof
People Clammering To Get On Buses
SOS Sign on The Roof Of A Flooded House
Restaurant Gone But The Sign Remains
Girl Who Lost Her Parents