The Red Cross is a good choice.
In this situation, donating cash to reputable organizations with Japanese partners able to turn this cash into emergency assistance is the best way to respond…Volunteers and bulk shipments from abroad, while well intentioned, will hamper the response by demanding precious time to organize and clogging runways, roads and other transport infrastructure.
The International Federation of Red Cross and Red Crescent Societies (IFRCRCS) is a reputable organization that includes the Japanese Red Cross Society as a member. Donations to the American Red Cross will be forwarded to the Japanese Red Cross Society.
UNICEF may be another good choice since it already has teams on the ground in Japan and representatives have said that 100% of the funds will go to Japan.
Make sure you know where your donation will actually go.
The Japanese Red Cross Society said that any funds collected that do not go to disaster relief efforts will go directly to the victims of the earthquake/tsunami.
Many charities have listed on their websites that they are “ready to go” to Japan with volunteers and goods, but according to Joel Charney and other experts, a new influx of international volunteers and goods may actually slow down the recovery effort. It is better to donate to organizations that already have disaster relief teams in Japan.
Transparency insofar as where disaster relief donations actually go is a major issue, according to GiveWell. Choose organizations that have publicly stated that the funds will only go to the disaster relief effort in Japan (see the list below). Otherwise your donation may be used for something other than direct disaster relief in Japan.
If you have the time, choose a website donation instead of a text donation.
According to Change.org:
During the response to Haiti, cellphone companies processed mobile donations to relief organizations right away. But for Japan, they aren’t making this same exception and it could take as much as 90 days for donations to reach people in need.
The transfer of your donations to relief organizations through text (SMS) messages could be delayed up to 90 days because cell phone service providers wait until the end of the billing cycle to transfer the money to relief organizations.
Another option is to donate through iTunes. Apple recently announced the availability of this option, and guaranteed that 100% of the funds would go to the American Red Cross. It is likely that the transfer of funds would be quicker with iTunes than with text messages.
Ask cell phone service providers to step up.
Sign the Change.org petition to stop the delay on donations to Japan, which urges cell phone service providers to send donation funds immediately instead of waiting till the end of billing cycles.
These organizations already have disaster relief teams or partners on the ground in Japan and have publicly stated that funds will go directly to disaster relief in Japan:
Note: GiveWell suggests that we reward Doctors Without Borders for being transparent and honest. Doctors without Borders has said that they would not earmark donations specifically for their disaster recovery efforts in Japan, which have already begun.