The phylogenetic diversity of microorganisms living at high salt concentrations is surprising and great as well. Halophiles are found in each of the three domains: Archaea, Bacteria, and Eucarya. Many archaea colonize extreme environments. They include hyperthermophiles, sulfur-metabolizing thermophiles, extreme halophiles and methanogens. Because extremophilic microorganisms have unusual properties, they are a potentially valuable resource in the development of novel biotechnological processes. Despite extensive research, however, there are few existing industrial applications of either archaeal biomass or archaeal products in centuries-old processes. Hence this review summarizes current knowledge about the biotechnological uses of archaea and archaeal products with special attention to potential applications that are the subject of current experimental evaluation which are of key importance for the development of new biotechnological tools.