Patricia Arquette and Rosetta Getty have started a foundation called Give Love to help the people of Haiti to rebuild after the earthquake. Their first project is to build temporary housing for some of the people who are still displaced after the quake. Future projects include developing low-cost, safe waste management systems, water treatment systems and so forth.
You can read more about her organization, and contribute if you are so inclined at her website.
She will also be appearing on a press radio tour on Thursday, March 25th to talk about her work in Haiti, and her organization.