Lyotropic liquid crystals (LLCs) are amphiphilic molecules that have the ability to self-organize into highly ordered yet fluid, phase-segregated assemblies in the presence of an added polar liquid such as water. The resulting ordered assemblies, called LLC phases, have specific nanometer-scale geometries with periodic hydrophilic and hydrophobic features ranging in structure from bilayer lamellae to extended and interconnected channel systems. Because of their highly uniform, porous nanoscale structures, LLC phases and LLC-based materials have been proposed for use in a number of materials applications. However, only during the last two decades have LLC materials with functional properties and demonstrated applications of LLC systems been realized. This work provides an overview of functional LLC materials and the areas of application where they have made an impact. As new functional properties and capabilities are realized in LLC materials, it is almost certain that they will play more prevalent roles in nanoscience and nanotechnology in the near future.