As you can imagine, there are dozens of organizations who are (or who are claiming to be) helping the victims in Haiti. If you have trouble choosing a charity, and/or want to know if the charity you're choosing is using the donated funds efficiently, you can research them easily on Charity Navigator. This site gives a breakdown of how much actually gets to the intended recipients, versus how much is spent in administrative costs, primary salaries, etc.

Ellen De Generis' website also has an easy list of charities - there are a few where you can text your donation on your cellphone - the amount is then added to your bill.