Topical synthesis databases provide integrated geochemical data for a specific topic of interest. Integration of geochemical data means that measurements, standards, and preparation are documented in a standard way, and delivered to the user in a single table from up to hundreds of original publications. Tabulation of such data by hand may take years, but synthesis databases have the benefit of years of operation. Examples of specific topics include ocean floor geochemistry PetDB, geochemistry of sediments SedDB, hydrothermal vent systems VentDB, xenoliths (Deep Lithosphere Data Set - now part of PetDB), Ar-Ar geochronology (Geochron), and North American volcanic rocks (NAVDAT) (Table 1).