Hurricane Katrina Recovery on FirstGov.gov

The United States government has collected links and information in these categories: Finding Loved Ones, Help for Victims, How You Can Help, Health and Safety, Government Agencies and Recovery Response. (Front page here.) For information in Spanish, see Huracán Katrina: Recuperación.

hat tip: NASA home page, which has employee check-in areas, information on NASA facilities affected by the storm, satellite images of flood areas, and more.

Update: Disasterhelp.gov also has a Katrina aftermath page.