OSGeo
Open Source Geospatial Foundation
OSGeo is a non-profit organization serving as an umbrella organization for the Open Source Geospatial community in general and several code projects in particular:
Web Mapping
deegree, geomajas, GeoMOOSE, GeoServer, Mapbender, MapFish, MapGuide Open Source, MapServer, OpenLayers
Desktop Applications
GRASS GIS, gvSIG, Marble, QGIS
Geospatial Libraries
FDO, GDAL/OGR, GEOS, GeoTools, OSSIM, PostGIS
Metadata Catalogues
GeoNetwork, pycsw
Content Management Systems
GeoNode
Other Incubating Projects
istSOS, MetaCRS, Opticks, Orfeo ToolBox (OTB), PyWPS, Team Engine, ZOO-Project
Other (non-code) Projects
GeoForAll (Education and Curriculum), OSGeo-Live DVD, Public Geospatial Data
We host regional and international FOSS4G conferences with typical attendance of 500-1000+ geospatial developers, industry and government leaders, and researchers. Our mailing lists collectively go out to ~ 28,600 unique subscribers.