Following up on Glenn’s post, I’ve just donated to and would recommend donating to the Union for Reform Judaism’s Disaster Relief Fund. They have an option to donate specifically for Katrina help, and 100% of your donation is used for relief. You don’t have to be a member or anything to donate (I’m not).
Check out Glenn’s post and follow along at Instapundit for further details and updates, and many more ideas for donating or otherwise helping out.
UPDATE: the truth laid bear is keeping tabs on Katrina relief and offers a comprehensive list of blogs and charities.
ANOTHER UPDATE: If you donate, or if you’ve already donated, don’t forget to log your contribution.