Also if you would like to do something else to help. You candonate to one of the international aid agencies like the Red Cross or Doctors without Borders because they are on the ground helping people in Japan.
Another thing to note is that Japan is the third richest country in the world, so they will be ok, financially (not to be taken in a bad way).
But countries like Haiti STILL need your help today. So if you are donating money to an aid agency you know that the money will go where it is needed, all over the world, all year around and not only during an earthquake or tsumani.
more details here
http://justhungry.com/japan-earthquake-how-help