If you're in the US and would like to donate to help any victims of the earthquake and tsunami in Japan, I would recommend making the donation to the American Red Cross. They set up a fund specifically for this disaster, and you can be assured your money will go towards helping those in need.
You can donate $10 by texting REDCROSS to 90999, or you can donate another amount by visiting the Red Cross' online donation site at
https://american.redcross.org/site/Donation2?idb=0&5052.donation=form1&df_id=5052
If you're in another country, you can donate online to the International Federation of Red Cross and Red Crescent Societies, which encapsulates all the various international Red Cross or Red Crescent organizations around the world:
http://www.ifrc.org/en/get-involved/donate/donation/
- Jason