As a consequence of their structural and dynamical properties, reversed micelles and water-containing reversed micelles have been employed as peculiar solvent and reaction media. In particular, inside their nanometer-sized micellar core have been incorporated nanoparticles of many different substances such as metals, inorganic salts and polymers. The aim of this contribution is to furnish to the reader a panoramic view of the methods employed to synthesize and of their unusual physico-chemical properties.