This is the post I put up on applying for FEMA aid after Hurricane Katrina. I know that almost everyone in Houston/Galveston can't access this, but if you have loved ones in the area, the best use of your time is to collect this information for them.
This is the link to applying for disaster assistance.
This is the FEMA link for Flood Insurance.
The American Insurance Association has a page dedicated to Natural Castrophes as well.
Finally, here is the Texas Department of Insurance page on the Hurricane Ike recovery, which includes links for volunteer activity, as well as links for contacting insurance carriers, Emergency adjusters and the like. It is a pretty good resource.