Gramps is an open source genealogical tool that is intuitive for hobbyists and feature rich for professional genealogists.  It is backed by an open community that supports research and is created and governed by professional genealogists.  Gramps will allow a user to track people, families, relationships, places, sources, citations, ancestry, media, history, and other information.  It also allows a user to generate reports on ancestors or descendants of an individual.  Translations exist for 31 different languages.  Gramps is available for Windows, Mac, Linux, and BSD.