I guess this has been around for a little while, but I just heard about it, and I think it's cool.
Kiva is a website that lets you lend small amounts of money ($25 or more) to small entrepreneurs all over the world to help them grow their businesses. The website has profiles of the entrepreneurs, including descriptions of what they want the money for. Most of the people are only trying to borrow a few hundred dollars. When you lend to someone, you get updates about how the business is doing, and as they pay the loan back, you get paid back. (Kiva's repayment rate to date is over 99%). Then you can cash out or reinvest in another business. Right now, you don't get any of the interest the borrowers pay, so it's a charitable act and not an investment. Here's how it works.
I've only heard bits and pieces about microfinance, and I know there are downsides. But for the most part, I think Kiva's model is really interesting. The loss of the interest on $25 or $100 for several months is not something most middle-class Americans would even notice, but that money could make a massive difference in someone's life. And unlike most traditional giving programs (which I also support), it could help build economies and sustainable occupations. And it's easy. And it encourages people who might not otherwise give to get involved.