The thesis is that the poorest people are a huge market and they need services and will pay for them. People who live on less then $10 a day have needs and they can be served if we listen.
Here is a great story about the progress of the Aravind Eye clinic, which is an Indian for profit eye clinic modelled on McDonald's. There is a lot to learn from and consider here. The gift of sight is delivered efficiently to many who would have never considered it possible. The ingredients are passion, entrepreneurial management thinking and drive.
I have a met few people who do this including life insurance for the poor and a specialist in mobile banking. These are mundane services in the developed world, but can be life changing in other parts of the world.
Full Disclosure: I am a TED video junkie. I haven't owned a TV in 20 years and am picky about films and shows I watch, but TED almost always makes the cut. If you want learn something interesting, check out some TED shows.