Here are a few of the organizations involved with rebuilding and relief efforts. If your time is not available,consider a contribution.
Musicians Village, a project of Habitat For Humanity and Branford Marsalis. A really interesting project, building a village of homes for displaced New orleans musicians.
Former presidents joining forces to help fund relief/rebuilding efforts for all communities affected by Katrina.
Oxfam America has been involved for many years with assisting the poor in building efforts.
This organization's volunteers live in the communities they serve. Don't know much about them, but they are very grassroots. Saw one of their sites in the lower ninth ward last year.