I found these sites via The Strobist.
Kiva allows microfinance institutions around the world, called “Field Partners”, to post profiles of qualified local entrepreneurs on its website. Lenders browse and choose an entrepreneur they wish to fund. Kiva aggregates loan capital from individual lenders and transfers it to the appropriate Field Partners to disburse to the entrepreneur chosen by the lender. As the entrepreneurs repay their loans, the Field Partners remit funds back to Kiva. As the loan is repaid, the Kiva lenders can withdraw their principal or re-loan it to another entrepreneur.