Several days after Columbia University's Edmund Phelps won the Nobel Prize in Economics for his theories about the relationship between inflation and unemployment, the Noble Peace Prize was awarded to a man with some useful ideas about economics. Muhammad Yunus of Bangladesh founded the Grameen Bank 30 years ago, where he invented the idea of "microcredit." Yunus showed that even loans as small as $12 will help the poorest people to buy a cow or a cell phone to start their own small business and then repay their loans. Today over 3,000 institutions in 130 countries have built on Yunus's ideas about microcredit.