Katrina is a pretty name -my cousin is called Katrina and it seems unbelieveable that hurricanes with almost friendly sounding names can cause massive devastation.
Its hard to know what to do when there are such horrific disasters- especially if you are thousands of miles away. Mostly giving money and raising awareness is the only way of helping, unless you are on the spot.
I've found some places to donate online:
America’s Second Harvest—The Nation’s Food Bank Network
Direct Relief International
American Red Cross
Convoy of Hope
this charity also accepts paypal donations
These all seem to be decent places to send money - most money goes to the disaster rather than to paying high salaries . I tried to check them out before posting them - most get 4 stars on the Charity Navigator.
Network for Good has a whole page of potential places to donate all in one place securely with details about each charity - plus information about the disaster and activity pages for explaining hurricanes and disaster preparedness to children. Also has pages about volunteer opportunites
Blogs trying to raise funds for Hurricane katrina Relief http://www.truthlaidbear.com/katrinablogs.php
Instapundit roundup page with suggested charities -all denominations and none http://instapundit.com/archives/025235.php
Some additional things that i think deserve poubliscity - Homes for Katrina Victims is coordinating a register for relatively local folk willing to take in people made homeless by the disaster. I wish this effort every success
Americans Aiding Americans is keeping note of donations by groups and companies -some of whom are matching donations made by their customers or employees which might be useful to folk in the US who are considering donating.
Other notable efforts can be found on Michelle Malkin's blog which is where i found the two above.