Microbial fuel cells (MFCs) are devices that exploit microbial catabolic activities to generate electricity from a variety of materials, including complex organic waste and renewable biomass. These sources provide MFCs with a great advantage over chemical fuel cells that can utilize only purified reactive fuels (e.g., hydrogen). A developing primary application of MFCs is its use in the production of sustainable bioenergy, e.g., organic waste treatment coupled with electricity generation, although further technical developments are necessary for its practical use. In this article, recent advances in MFC technologies that can become fundamentals for future practical MFC developments are summarized. Results of recent studies suggest that MFCs will be of practical use in the near future and will become a preferred option among sustainable bioenergy processes.