Another alternative for donations is the Mennonite Disaster Service.
http://mds.mennonite.net/My friends and I often donate to disaster relief through this organization (and no, we're not Mennonite).
It's a faith-based group that does not seem to force its faith on people -- they focus on "touching lives" by helping people clean up and rebuild. They're already going into areas hit by Katrina to start helping the cleanup and rebuilding.
"While our main focus is on clean up, repair and rebuilding homes, this activity becomes a means of touching lives and helping people regain faith and wholeness."
This group also helped with the tsunami and other disasters. They're a good group to donate to, if you're uncomfortable with the Red Cross.
Living in Lancaster County, PA, I know several (non-Mennonite) people who work or have worked for the related Mennonite Central Committee, because they really believe in the work this group does.
They're already rolling up their sleeves. From the Web site:
MDS Starts Katrina Response
MOBILE, Alabama September 3 -- Significant progress has been in an MDS response to Hurricane Katrina. Investigation teams traveling in the hurricane-affected region have begun identifying response sites. Three areas will activate this weekend with two groups starting today .
First, Gulfhaven Mennonite Church, in Gulfport , Mississippi has agreed to become a staging area for work teams. The first group, made up of small work teams from the church congregation will begin working in Gulfport this weekend. Second, a small team will begin doing chainsaw cleanup work this morning in the Meridian area. The group will work through the weekend with a larger group supplementing them early in the week.
Third, a team from Lancaster County, Pennsylvania will arrive in Mobile, Alabama Sunday night. The group will stage out of Mobile and begin chainsaw and cleanup work in the storm- damaged area southwest of the city.