If you're making more than a percent or two interest in what you believe is warm-fuzzy charitable lending, you're simply deluded. Almost all of these enjoy double digit interest rate yields... that's after losses for defaults. Most are around 30% some over 80%. It is very obviously a morally bankrupt practice which has managed to clothe itself as a charity.
I'm not disagreeing with you, and recall reading elsewhere about Kiva's deceptive practices, but could you back up that claim with some evidence, or at least a more detailed explanation?
This is why I've stopped believing in giving to on-the-door charity pleas, or give-some-money-to-X-before-you-check-your-goods-out-at-the-checkout. It seems much better to properly research one or a handful of organizations and give to those, than to give to organizations you have hardly heard of because of the immediate social pressure.