General
http://www.giscafe.com
http://sunsite.berkeley.edu/GIS/gisnet.html
http://monarch.gsu.edu/jcrampton/maps

Data
http://www.gisdatadepot.com
http://www.geographynetwork.com

Jobs
http://www.geojobsource.com
http://www.gjc.org
http://www.giscareers.com

Organizations
http://www.asprs.org (ASPRS: The Imaging and Geospatial Society)
http://www.acsm.net/cagis (Cartography and Geographic Information Society)
http://www.aag.org (Association of American Geographers)
http://www.ncgia.org (National Center for Geographic Information and Analysis)
http://www.ucgis.org (University Consortium for GIScience)
http://www.nacis.org (North American Cartographic Information Society)

Government
http://www.usgs.gov (U.S. Geological Survey)
http://www.census.gov/geo/www (U.S. Bureau of the Census)
http://www.phila.gov/mois (Office of Information Services, GIS Services Group)
http://www.pasda.psu.edu (Pennsylvania Spatial Data Access)
http://www.pamagic.org (Pennsylvania Mapping and Geographic Information Consortium)
http://www.state.nj.us/dep (New Jersey Department of Environmental Protection)

Companies
http://www.esri.com (ESRI – GIS)
http://www.autodesk.com/gis (Autodesk – GIS and CAD)
http://gis.leica-geosystems.com (Leica Geosystems - Erdas)
http://www.spaceimaging.com (SpaceImaging – Remote Sensing)
http://www.galaxymaps.com (Galaxy – Cartography)
http://www.delorme.com (DeLorme – Cartography)