If you want to be a lender, you choose a specific business, give Kiva an amount to loan($25 minimum), and when the full amount is loaned, the business gets their money. There's a small chance that you might lose the money if the business fails, but if all goes well, when the business pays the loan back in a couple of years, you get your loaned amount back. (It's an interest-free loan, so all you get is your money back.)
There are lots of neato businesses there-- hair salons, bookstores, construction workers who need tools, and so on. It also tells about the family situations of everyone; lots of folks are supporting their parents or younger siblings on their income, and need help to expand their business or buy equipment.
So, what do you folks think?