Hi all,
   Just sharing a link I received from our Data Science Center, which you may know about already.  This topic-centric list is updated frequently, and is indeed "awesome."  See especially the "GIS" section which includes U.S. sources, U.N. environmental data, Pleiades and others.
https://github.com/awesomedata/awesome-public-datasets

Cheers,
Louise

Louise Ratliff
Social Sciences and Map Catalog Librarian
UCLA Library Cataloging & Metadata Center
2400 Life Sciences Building
Box 957230
Los Angeles, CA 90095-7230
(310)206-5853