The American Red Cross is taking donations. You can even specify where you want the donation to go.
The British Red Cross has a disaster fund, if not a special fund for the earthquake victims.
The Salvation Army is accepting monetary donations.
Convoy of Hope is already helping the earthquake and tsunami victims, and is accepting donations.
Network for Good--a collection of charities--is working to give relief to the victims of the quake and tsunami. The organizations participating are:
( relief for your flist )
You can also go to help_japan on LJ. They're having a fandom auction, starting on March 14th. All proceeds are going to vetted charities.