What can the United States do than what they have already done to help the Haitians. When the US arrived in Haiti there was a logistical and security nightmare to sort out, but they quickly got the airport up and running, as smooth as they could, so aid and personnel could get into Haiti.
Yes more can be done, but why should the US take it all on their shoulders.
No matter what the US does they are in the wrong according to some other countries.
The most I, or any member of the public, can do is donate to a charity to help Haiti, but what about other countries governments.
If you go here, there are pictures of the personnel from a number of countries helping in the relief effort in Haiti.
Where is the help from the more wealthy nations of the world, like Saudi Arabia.
Here is a quote to an article in the Telegraph today, to answer that question.
Compare this with the response to the disaster in the Arab states, where the US is so routinely reviled. Some of the poorest among them, such as Jordan and Lebanon, have sent assistance, as have the United Arab Emirates and Qatar. But Saudi Arabia, one of the world's wealthiest nations, has managed to send just a letter of condolence. As for Syria, which never misses an opportunity to denounce the iniquities of the Great Satan, it appears to have sent nothing at all.
The US doesn't get it right all the time, what country does, but what other country has ships, aircraft, personnel to mount this sort of operation with so many assets at their disposal.