This paper describes some of the main aspects of microfinance (MF) in under-developed countries, showing why it has succeeded in reaching the poor, while traditional banks have not, using innovative devices such as group lending with self-monitoring, short repayments instalments and small loans. The aim of the paper is to show how microfinance institutions (MFIs) can fill the lack of traditional banks in under-developed countries, proposing unconventional products and innovative business models. This study also investigates about possible synergies between banks and MFIs, avoiding overlaps and mission drift. It is shown that MFIs can improve their outreach using technological devices such as M-banking. Innovative questions and proposals are illustrated, so as to give an updated and synthetic picture of the state-of-the-art, which might prove useful for researchers and practitioners.