PostGIS adds support for geographic objects to the PostgreSQL object-relational database. In effect, PostGIS "spatially enables" the PostgreSQL server, allowing it to be used as a backend spatial database for geographic information systems (GIS)
Open Aerial Map is a non-profit, open access, meeting place for the aerial imaging community. It exists to provide a freely available image map of the world created solely by community contribution, and to facilitate the free exchange of imagery, technology, and ideas. In order to provide an unrestricted, free, an unbiased view of the world, OpenAerialMap encourages the free exchange of aerial imagery, without restriction on its use.
gMapMaker enables you to make OziExplorer compatible maps (merged image + .map calibration file) from Google Map tile images (satellite, hybrid, driving maps)