The biggest, SKS, was launched by VikramAkula as a charity, with (according to his divorced and embittered wife) donations from the guests at their lavish wedding.
Read with interest the discussion between Prof Yunus and VikramAkula. i believe they have both taken extreme positions and hence not of much value to the rest of us.
Recently SKS founder VikramAkula (which also has billionaire Vinod Khosla and Sequoia Capital as investors), got into this very debate with his one time idol, Muhammad Yunus, the Nobel Prize founder of Grameen Bank and the father of microfinance.