"...a distributed digital library with collections of georeferenced materials." Provided by University of California Santa Barbara

"Search, discover, preview, and retrieve geospatial data from multiple repositories." Tufts University

Both free and for fee data holdings. May require access to GIS software.

Share your live authoritative open data. Esri-hosted ArcGIS Open Data gives you a quick way to set up public-facing websites where people can easily find and download your open data in a variety of open formats.