canadiangis.com
Grass GIS Software - Canadian GIS & Geomatics
GRASS GIS, commonly referred to as Geographic Resources Analysis Support System, is an open source GIS software that is commonly used for geospatial data analysis, data management, image processing, cartography, spatial modeling, and data visualization. It contains over 350 modules to help render maps, offers both an intuitive graphical user interface as well as command line, and is free!