Biology

Digital Elevation Model (DEM) data for coastal locations in the US.

Flood insurance maps and geospatial data from the Federal Emergency Management Agency

Portal to discover US government geospatial data.

Dates: 1790-2011
Free of charge, aggregate census data and GIS-compatible boundary files for the United States.

GIS data, maps, and geospatial visualizations from the USGS.

Links to several different sources of GIS data for Connecticut.

GIS data from the state of New York.

Massachusetts maps and GIS data.

RI GIS data from the RI state government and the University of Rhode Island.

Spatial dataset of the world's administrative areas/boundaries for GIS.

Mainly raster satellite data from a wide variety of sources.

Vector and raster data of global cultural and physical features at a number of different scales.

Map-based interface to discover global population and environmental data.

GeoTIFF files for 1970 to 2000.

Part of the IUCN Red List project.

Geospatial data from the Geopatial Management Office of the Department of Homeland Security

Geographical interface for viewing and download data from the IUCN's World Database of Protected Areas.

Find KML and KMZ files which can be converted to .shp files in ArcGIS.

Pro version now free and much more powerful than regular Google Earth

Free file compression software for Windows

7-Zip for Mac OS