QGIS
QGIS, formerly Quantum GIS, is a user friendly open source Geographic Information System (GIS) licensed under the GNU General Public License that runs on Linux, Unix, Mac OSX, and Windows and supports numerous vector, raster, and database formats and functionalities. QGIS lets you browse, edit and create a variety of vector and raster formats, including ESRI shapefiles, spatial data in PostgreSQL/PostGIS, GRASS vectors and rasters, or GeoTiff. You can create customised plugins and GIS enabled applications using Python or C++. Maps can be compiled for printing using the print composer. QGIS supports plugins to do things like import of delimited text data, download tracks, routes, and waypoints from your GPS or visualize OGC WMS and WFS layers.
