A warning - FEMA has a list of organizations taking cash donations. One of the top on the list is Operation Blessing
. This is radical cleric Pat Robertson's organization. I suspect money you send him is more likely to be invested in race horses than given to flood victims. Or maybe he'd use it to hire a hitman given his comments last week about Hugo Chavez.
The other organizations on the list seem good. My money went to the Salvation Army. I don't share their religious beliefs, but they're reliable and honest. When you need them they're there.