It is becoming well-known that bacterial cells produce membrane vesicles (MVs) from the cell surface in a budding manner, whereas the detailed mechanisms of MV biogenesis remain unclear. MVs are not authentic cells, since they are observed to be between 20 and 300 nm in size but have a structure close to the subcellular compartments. In a sense, the structure of MVs containing biogenic and cellular substances and their behavior look similar to those of viruses. Due to these scientific facts, several potent applications employing MVs as a promising tool have been proposed and reported. This review introduces a few outstanding examples for promising applications of MVs to biotechnology.