Lambda Chi Alpha has created a website for all inter/national fraternities and sororities who have chapters it the affected areas.
http://www.fraternalrelief.org
As of 2:30 CDT on 9/1/05 the following groups are participating and have individual links to the status of chapters/members in Katrina's wake:
Delta Chi
Delta Tau Delta
Delta Upsilon
Lambda Chi Alpha
Phi Delta Theta
Phi Kappa Sigma
I am sure the list will grow as the devistation continues to be discovered.