Katrina People Finder/Future
A quick note in case you have time to volunteer now or think you can use it: Ethan Zuckerman and some associates have built something called the Katrina People Finder to try and systematically collect and reconcile all the different Craigslist/newspaper type bulletins into a single, searchable database. They've designed a data-set standard and have so far had 2100 volunteers enter put together 68,000 records. They need volunteers both with the programming and the data-entry.
Ruchira has a good post on things we'll need to keep worrying about--housing, counseling, and credit-rehabilitation. We should start chewing on it now so that some brilliant mind comes up with another idea like above.
Update: It looks like they're done, for now; at least some kind of searchable interface is up at KatrinaList.net. Hopefully this will help people find their loved ones, or at least keep track of who is still missing. Ethan wrote up his view of the timeline in his blog. Fascinating.