The phase behavior of surfactant-oil-water mixtures gives rise to a wide variety of possible equilibrium systems, including microemulsions. The Figure shows one model for a gelatin-containing microemulsion-based organogel deduced from data from small-angle neutron scattering. The conditions required and the stability of microemulsions are briefly reviewed before their applications, and the supramolecular architectures they provide, are considered in more detail.