Charity Navigator is a good resource to use when deciding how to donate to the relief effort.
Here are some libertarian views on the government's handling of the Katrina disaster:
The State and the Flood
Catastrophe in Big Easy Demonstrates Big Government's Failure
Katrina Exposes Government for What It Is
Military Occupation in America and the Prospects for Liberty
The Day the Glue Came Undone
A Monopoly on Life
No Thanks, Leviathan
Lessons from the Debacle
Freedom's Fair Weather Friends
Leave New Orleans to Private Development
A collection of articles and commentary on the gun confiscations can be found here:
Gun Confiscation In New Orleans
Gun Grab Gambit Goes Great in New Orleans
9/15/05 - Gun Confiscation Kept Quiet
9/23/05 - Federal Judge Halts New Orleans Gun Seizures
11/22/05 - Gun Confiscation: Never Again in Louisiana
Reason Online recently ran an article about the falsehoods spread by the media in the wake of the disaster.
Also note that the Libertarian Party homepage included several stories of libertarians involved in the relief effort in the weeks following the disaster.