Kiva.org is a great legitimate program that supports micro-finance.
I have done 2 loans and I can withdraw at a later date if I need the money back.
I would say about 90% of the loans are paid back totally but with micro-finance the risk is spead across multiple projects so your total risk is low.
Give it a go for free at http://www.kiva.org/invitedby/tim1740