The American Red Cross
Text "Haiti" to 90999 to donate $10 (billed to your phone)
The United Nations World Food Program
The Salvation Army
Hands on Disaster Response
Action Against Hunger
Partners in Health
Please add (in comments) if you know of other organizations.
Are YOU prepared for a natural disaster? Get trained for your local Community Emergency Response Team. Start the online portion now at http://www.citizencorps.gov/cert/. You will need to take classroom training afterwards to complete your certification.