The Statistic I'd Like to See
In personal conversations and in the media, the U.S. government has been criticized for not offering more aid quicker. After their initial pledge of $35 million, Democracy Now! compared that to just four hours of fighting the Iraq war. Colin Powell pointed out that the $35 million was just the first of many checks the government would give to tsunami victims. Currently, the gov't's pledged $350 million, but was one-upped by Japan pledging $500 million.
I think that touting just the amount that governments pledged is misleading. Usually, the comparisons leave the impression that the U.S. isn't doing its fair share as the world super power, or at least that it's not as generous as other countries. But this ignores the contributions of private businesses and individuals. Democracy Now!'s comparision was especially inappropriate since the government is the sole entity that is legally allowed to wage war, whereas many entities may donate money to relief efforts.
Rather than comparing the U.S. gov't's pledge to Japan's, a better comparison would the the sum of U.S. citizens', businesses', non-profits', and government's pledges to the sum of other countries.
I don't think tablulating such statistics would be difficult. I've seen numbers of total aid pledged (around $2 billion so far), and it shouldn't be hard to break that down by country. Such a tally would be a more accurate reflection of a nation's total contribution.
Update: The Economist had exactly these figures in their January 6 issue. If you subscribe, you can access the article here. In total, the US still trailed behind Australia, the EU, and Germany.
Update 2: The Economist has an update table, which puts the US in the number 2 spot in terms of government plus private donations, behind Australia. Private donations from the US are greater than any other country. Germany is second in private donations, and Britian is third.