I once thought about this a bit and did some research. There are a few nascent companies which are trying this out. One such is Greenshoe [Refer to this article
]. I think there are one or two which operate only in India, mostly within the microfinancing or microlending framework. There is quite a bit of regulations in that sector given the prior work of a few companies and non-profits. For example, see this Kiva page
, which also contains links to RBI regulations.
If you are interested in this, let's catch up.