On a similar note, I have heard many nasty things coming from people about these disasters, saying that it is "karmic retribution" from the Pearl Harbor attacks, or possibly from their whaling operations. These talks do nothing but anger people, and makes you look like fools. I beg of you to think before you say or type anything, and try to be mindful of others' feelings.
Here is a list of several organizations to donate to:
Mercy Corps: dial 888-747-7440, or go to http://www.mercycorps.org/donate/japan
American Red Cross: dial 800-733-2767, or go to http://www.redcross.org/
There are many other options, but those two organizations are probably the most reputable ones that I know of. You can go to any one you want, but I would be cautious if it is an organization you haven't heard of.