Remittances are US dollars that foreign nationals earn in the US and send back to their home country. On net the US sends out more dollars than are returned to the US by US citizens living abroad and sending payments home.
Pew Research (a bonanza for blog fodder lately!) has a nice interactive map and data on remittances.
Here are Top 30 destinations for US dollars being "exported" abroad:
Here is a 2010 list of the Top 25 recipients of US Foreign Aid (tax dollars). I highlighted the countries that appear on the remittance list above too. In several cases, the residents of these countries are in the working in the US and sending home MORE US dollars than we send them in foreign aid.