This chapter gives an overview of the range of cyanobacterial materials being harvested from nature and grown in culture, increasingly on a large scale. Arthrospira, which is usually marketed as Spirulina, is the most important, but studies are also underway on developing methods to grow Nostoc commercially; at present colonies of several species are harvested for local use in a number of countries in Asia, Africa and South America Although Aphanizomenon flos-aquae has been harvested and sold, the costs of the quality control needed to avoid long-term risks of material including toxins makes its large-scale culture unrealistic. The various approaches to mass culture are considered and the ways in which cyanobacteria are now being used are described. These include food, phycobiliproteins for pigment and antioxidant, animal feed, cosmetics, biofertilizers and treatment of wastewater and exhaust gas. Promising products for the near future include some of the huge range of bioactive molecules produced by cyanobacteria and most important of all, biofuel.