Kiva.org is a remarkable organization in at least a couple ways - they employ micro-finance principles to aid entrepreneurs in developing countries, and they make excellent use of online technology to do so. We highlighted them in my International Aid and Development class in college.
I really like that they're using the Long Tail on both the lending side and the receiving side of micro-finance. I also like some of their cool web features - the portable badge above, and their use of Facebook Connect to syndicate their activity to Facebook.
One of our good friends gave us a $25 gift certificate to Kiva and I think it's one of the best gifts we've ever received. I've admired Kiva for a while but have never spent the time or effort to get involved with it; this small amount is really inspiring me to do more.
UPDATE: Wow. When I picked my loan recipient, Margaret, she had 0% of her requested loan. In the 1-2 hours it took to get this blog post up, she received 100% of it. Go Kiva! Go Margaret!