Microfinance, where entrepreneurs in developing countries are loaned a few hundred dollars or less to start a business is a well studied and popular policy tool. For those who want to get involve I have discussed Kiva in the past.
But, my dad passed on a new website called matchsavings.org Instead of giving out loans like Kiva you provide money to match the savings of people in developing countries. Like Kiva you can choose the person you watch to provide a match for, although the selection is limited to a few Mexican communities for now.
The website is run by the World Council of Credit Unions, whose home is in Madison Wisconsin. I know of the organization and it has a good reputation and experience in providing financial services in developing countries.