Direct Relief International is one of the organizations helping the hundreds of thousands of Tsunami victims. I recommend donating through them, as they are highly respected and received a 100% efficiency rating from Forbes: Less than 1% of the money they receive goes toward administrative and advertising costs. Additionally, they have corporate sponsors who match contributions by private individuals: "In 2003, Direct Relief International was able to deliver $3,400 in medical aid for every $100 donated!"
Here's the link to their online donation page. If you can spare a small contribution this holiday season, please consider donating to them today--the sooner the better. And please encourage others to do so as well.