Nature has an article about an organization in India called Jodo Gyan that provides educational services to underprivileged children. One of their products, a bamboo microscope that costs only $4, is attracting particular attention. Not surprisingly, the inexpensive device is in high demand. Microscopes are a great way to engage kids in science - looking at something they can't otherwise see can be very cool. However, making one for $4 could be transformative - now if we can just get some to the U.S.
A quick Google search found that Jodo Gyan considers itself a social enterprise (as opposed to a not-for-profit or NGO). They create products and deliver services to engage kids in learning in effective ways.
Link to Nature article
(Thanks to BoingBoing for the reference)