Ebrary just announced a new online resource called the Natural Disaster & Extreme Weather Searchable Information Center. They've gathered in one place public domain PDFs, and created more PDFs from web pages, Word documents, and other file types
I've always wanted to take a deeper look at the Katrina disaster, so I looked at the Katrina records (26 documents) to see how well ebrary recorded that disaster. I'm not impressed. Obviously the collection can only be as good as the source material, and that was lacking in detail.