Japan's earthquake last week was the largest in the country's recorded history, and the subsequent tsunami even more terrible in its devastation and destruction. Now the Japanese people must rebuild their communities, while mourning their dead and caring for the injured and displaced.

They will need our help. Many of us are desperate to do something, but perhaps don't know how best to assist the victims of this horrific catastrophe. What do the Japanese people need most right now? Which charities are most effective in providing relief to the region? Does Japan really need money at this particular time? These are just a few of the questions that Americans are wondering about at the moment.

What to do
Seeking answers to these questions yesterday, I spoke with Sean Milliken, who is the executive director of MissionFish, the administrator of eBay's (Nasdaq: EBAY) Giving Works program. Sean told me that in times of disaster, donations of goods are not helpful, as they pose additional logistical problems for the organizations on the ground. Instead, donors should offer cash, which is of paramount importance.

There are numerous ways of offering cash donations, according to Sean. First, you can find lists of leading charitable organizations on major news sites. Be sure to click on the links to the listed charities' websites in order to read more about them. You can then research your selections on Charity Navigator, a site that is devoted to intelligent giving. It will provide you with ratings and additional operational information on more than 5,000 charities.

In the table below I've provided links to some of the leading charities -- along with their ratings -- that are providing relief to Japan:

Charity Charity Navigator Overall Rating
American Red Cross 55.48
Save the Children 63.97
AmeriCares 64.49
Mercy Corps 52.66
World Vision 62.98

Source: Charity Navigator.

Sean also suggested that you might consider donating to the Network For Good, which will distribute your donation across a wide array of participating charities.

In addition to donating directly to the various charities, prospective donors can also give via other websites. eBay, Amazon.com (Nasdaq: AMZN), Google (Nasdaq: GOOG), Zynga, and PayPal have chosen to offer a wide variety of creative ways to support Japan relief efforts. For example, Zynga, an online provider of social games, has raised more than $1 million so far by partnering with Save the Children and allowing its players to make donations within its games. On eBay, assisted by Sean's company MissionFish, you can support a wide variety of charities through your buying and selling activities.

Finally, potential donors can give via their mobile devices. Below is a list of possible options in the U.S.:

Text Give
JAPAN to 20222 To donate $10 to Save The Children
MERCY to 25283 To donate $10 to Mercy Corps
REDCROSS to 90999 To donate $10 to American Red Cross
4JAPAN to 20222 To donate $10 to World Vision

Right time, right place?
Over the past several days, there has been a spirited online debate as to whether now is a good time to donate money to Japan. The blogger Felix Salmon, for example, argues that Japan is a wealthy country that has plenty of money to help out its citizens. Others argue that Japan needs our help during this difficult time, and that there are a lot of fine organizations out there who can provide that assistance in a timely and efficient way.

Personally, I'm a firm believer in the latter argument, and gave $250 to AmeriCares yesterday to assist with its efforts to help tsunami survivors. I've heard and read great things about that organization, and am very happy to support its work.

If you also decide to contribute to Japan relief, be sure to spend some time researching your organization, and make sure you are reasonably comfortable with it before making your donation.

Japan is a great nation, and I know that it will emerge from this crisis stronger than ever before. If anyone has additional ideas on how we might support the relief effort, feel free to share them in the comments box below.

John Reeves owns shares of Google, but none in any other company mentioned above. Amazon.com and eBay are Motley Fool Stock Advisor picks. The Fool owns shares of Google, which is a Motley Fool Inside Value and Motley Fool Rule Breakers recommendation. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.