http://betterref.net/ Search engine for artists looking for better reference
https://search.marginalia.nu Independent search engine that focuses on non-commercial content
http://www.loc.gov/pictures/search/?st=grid&co=wpapos Library of Congress graphic design
http://www.lamptech.co.uk/Catalogues.htm historical lamps
https://www.gianninigarden.com/online-catalog/ garden ornaments
https://sword-site.com/ High res sword photos & information
http://www.primeportal.net/home.htm Very slow but high res military photos
https://empirecmd.com/61-weapons-library Guns
http://modernfirearms.net/en/ Modern firearms
https://www.flickr.com/photos/royalairforcemuseum/albums UK Royal Air Force
https://weaponsystems.net/ Provides a full and complete overview of world wide used weapons.
https://www.flickr.com/photos/137994134@N07/albums/with/72157666781218675 History of aviation photography
https://www.imfdb.org/wiki/Main_Page Movie weapons database
https://www.flickr.com/people/142890043@N06/groups/ Big collection of train photography groups
https://pinterest.com/tbiliter/ medieval armor related things
pinterest.com/macs_shop/ mostly medieval armor related things