Definition from Answer.com:
Microloan is savery small, often short-term loan made to an impoverished entrepreneur, as in an underdeveloped country.
The 2006 Nobel Peace Prize given to the founder of Grameen Bank Muhammed Yunus has raised the world's awareness of this form of support to the poor.
"The Norwegian Nobel Committee has decided to award the Nobel Peace Prize for 2006, divided into two equal parts, to Muhammad Yunus and Grameen Bank for their efforts to create economic and social development from below. Lasting peace can not be achieved unless large population groups find ways in which to break out of poverty. Micro-credit is one such means. Development from below also serves to advance democracy and human rights.
Every single individual on earth has both the potential and the right to live a decent life. Across cultures and civilizations, Yunus and Grameen Bank have shown that even the poorest of the poor can work to bring about their own development.
Micro-credit has proved to be an important liberating force in societies where women in particular have to struggle against repressive social and economic conditions. Economic growth and political democracy can not achieve their full potential unless the female half of humanity participates on an equal footing with the male.
If you are interested in helping, check out the list in Wikipedia.