Flickrs of a tragedy
You can find a nice-sized archive of the pictures that the Reuters and AP photographers have taken here, but that's been filtered and vetted. And it's nothing compared to what you can find on Flickr at the moment.
I did a simple search for New Orleans and flooding and found some amazing stuff.
Sure, there aren't any from-the-helicopter angle shots, but there's a montage of a helicopter rescue on a hospital roof, among others.