Title: GeoServer
Vendor: Open Source
Web Site: http://geoserver.org/
Type: Raster/Vector/Tile
Focus: OGC Compliant WMS/WFS/WCS server.
Platform: Java
Price: Free
Description:
A Free/Open Source geospatial information server and the official reference implementation for the OGC standards. In simple terms, it is a program that can provide the data to run a "slippy map" like Google Maps, Bing Maps, etc. It can also provide data to plug into a GIS.
Examples: Vancouver Island Community Groundwater Mapping Project
Title: uDig
Vendor: Refractions Research
Web Site: http://udig.refractions.net/
Type: Vector, Raster.
Focus: Desktop GIS
Platform: Java
Price: Free
Description:
A somewhat simpler desktop GIS written in Java.
Examples:
Title: GRASS
Vendor: Open Source Geospatial Foundation
Web Site: http://grass.fbk.eu/
Type: Vector, Raster.
Focus: GIS
Platform: Multiplatform, Unix Oriented
Price: Free
Description:
Probably the most advanced, powerful, and flexible Open Source GIS, though the interface is a bit arcane.
Examples: