Determining the geometry and dynamics of the inner-most parsec of active galactic nuclei (AGN) is critical for understanding accretion and the relationship between the AGN and host galaxy. Water maser emission at 22 GHz provides a unique resolvable tracer of warm, dense molecular gas in the central parsec AGN. Studies of individual systems can be used to determine a broad array of the properties, including supermassive black hole mass, distance to the host galaxy, geometry of the accretion disks and outflows. In addition, population studies of masers offer clues to the relationship between maser emission and the AGN that host them and can be used to test theories of accretion. In the talk, I will discuss both individual maser systems, focusing on a rare disk maser in a dwarf galaxy, and population studies, in particular using masers to probe the temperature profile of accretion disks and correlations of maser properties with host AGN activity and SMBH mass.