Links to other GIS data sources

Census:
ESRI TIGER Census 2000 data interface
National Historical Geographic Information System-aggregate census data and GIS-compatible boundary files for the United States between 1790 and 2000
United States Census Bureau TIGER
Data for Decision: Three part series (short) of Canada's Land Inventory Geo-Information System

Elevation & Benthic:
ASTER DEM-higher latitude than SRTM data (registration required–free)
Consortium for Spatial Information (CGIAR)-filled global 90m SRTM data
USGS CLICK LiDAR viewer-PA las files are being posted here but not complete ( This site may be offline. )
NOAA Digital Coast–coastal and nearshore benthic data sets including LiDAR
Open Topography LiDAR portal
Puget Sound LiDAR Consortium-LiDAR data for Washington and Oregon


Imagery:
NASA Goddard Space Flight Center Global Change Master Directory ( This site may be offline. )
University of Maryland Global Land Cover Facility–LANDSAT and other satellite imagery ( This site may be offline. )

Maps-historic and otherwise:
Ask the Cartographer
ArcGIS online Standard Map collection (free for non-commercial use)
new ArcGIS resource center (Groups > ESRI Data and Maps, 17 pages of data)
David Rumsey historical map collection
East View Geospatial-great source for hard to find geologic maps-will scan and georeference from their collection
Historical GIS Boston 1775

Others:
National EPA Geospatial data page
National Operational Hydrologic Remote Sensing Center
National Snow and Ice Data Center
USDA National Resources Conservation Service Geospatial Data Gateway (more info)
Color Brewer : Color selection tool for visualizing quantitative data out of Penn State