Flickr (http://www.flickr.com/) is an online photo and video management and sharing application. Free accounts have 1 Terabyte of storage, paid accounts have 2 Terabytes. Photos can be tagged for easy searching and arranged into sets (a group of photos) and collections (a group of sets). Photos can also be geotagged and organized on a map.

Europe

National Museum of Denmark: http://www.flickr.com/photos/thenationalmuseumofdenmark/
National Library of Sweden: http://www.flickr.com/photos/95520404@N07/
Tate Gallery (UK): http://www.flickr.com/photos/tategallery/
Cornell University Library: http://www.flickr.com/photos/cornelluniversitylibrary/
The Reykjavík Museum of Photography: http://www.flickr.com/photos/reykjavikmuseumofphotography/
National Archives of Norway: http://www.flickr.com/photos/national_archives_of_norway/
Museum of Hartlepool: http://www.flickr.com/photos/hartlepool_museum/
Stockholm transport Museum: http://www.flickr.com/photos/stockholmtransportmuseum_commons/
National Library of Ireland on the Commons: http://www.flickr.com/photos/nlireland/
National Library Scotland: http://www.flickr.com/photos/nlscotland/
Swedish National Heritage Board: http://www.flickr.com/photos/swedish_heritage_board/
Stockholm University Library: https://www.flickr.com/photos/60610090@N04/collections/72157644956544616/

Asia-Pacific Region

State Library of Queensland (Commons): http://www.flickr.com/photos/statelibraryqueensland/
Tasmanian Archive and Heritage Office: http://www.flickr.com/photos/tasmanianarchiveandheritageoffice/
Australian National Maritime Museum on The Commons: http://www.flickr.com/photos/anmm_thecommons/
National Library of Australia the Commons: http://www.flickr.com/photos/national_library_of_australia_commons/
Queensland State Archives: http://www.flickr.com/photos/queenslandstatearchives/
State Library of Victoria, Collections: http://www.flickr.com/photos/statelibraryofvictoria_collections/
State library of Western Australia: http://www.flickr.com/photos/statelibrarywa/
National Maritime Museum (Australia): http://www.flickr.com/photos/nationalmaritimemuseum/
State Library of South Australia: http://www.flickr.com/photos/state_library_south_australia/sets/
Australian War memorial collection: http://www.flickr.com/photos/australian-war-memorial/
National Library New Zealand on the Commons: http://www.flickr.com/photos/nationallibrarynz_commons/
Powerhouse Museum (Sydney): http://www.flickr.com/photos/powerhouse_museum/
State Library of New South Wales: http://www.flickr.com/photos/statelibraryofnsw/
Special Collections, University of Melbourne: http://www.flickr.com/photos/uomspecialcollections/

USA

Special Collections & Archives, George Mason University, http://www.flickr.com/photos/gmuarchives/
Special Collections, Colorado College (within Tutt Library's Flickr), http://www.flickr.com/search/?w=69225135@N00&q=special%20collections
Archives & Special Collections, Amherst College, http://www.flickr.com/photos/amherst_college_archives/
Special Collections Center, University of Pennsylvania (Penn Provenance Project), http://www.flickr.com/photos/58558794@N07/
Special Collections, Augustana College (Rock Island, Illinois), http://www.flickr.com/photos/augustanaspecialcollections/
Library Company of Philadelphia, http://www.flickr.com/photos/library-company-of-philadelphia/
Ohio University Libraries, Mahn Center for Archives & Special Collections http://www.flickr.com/photos/ohiouniversitylibraries/collections/72157625174047285/
Jerome Lawrence and Robert E. Lee Theatre Research Institute, The Ohio State University, http://www.flickr.com/photos/60966199@N08/sets/72157626312413421/
Miami University Special Collections and Archives: http://www.flickr.com/photos/muohio_digital_collections/
Rare Books and Special Collections, Northern Illinois University, http://www.flickr.com/photos/62246028@N05/
Rare Book Collection, Lillian Goldman Law Library, Yale Law School, http://www.flickr.com/photos/yalelawlibrary/
Special Collections, University of Glasgow Library, http://www.flickr.com/photos/uofglibrary/collections/72157617896585255/
Archive Services, University of Glasgow Library, http://www.flickr.com/photos/uofglibrary/collections/72157617984143404/
San Francisco Public Library: http://www.flickr.com/photos/sfplsanfranciscohistoricalphotographcollection/
University of Scranton Weinberg Memorial Library, http://www.flickr.com/photos/universityofscrantonlibrary
The Texas Collection, Baylor University, http://www.flickr.com/photos/texascollectionbaylor
Florida Memory, State Archives of Florida, http://www.flickr.com/photos/floridamemory/
Beinecke Rare Book & Manuscript Library, Yale University, http://www.flickr.com/photos/beinecke_library
The Grolier Club, http://www.flickr.com/photos/grolierclub/
Southern Folklife Collection, University of North Carolina at Chapel Hill: https://www.flickr.com/photos/southernfolklife/
Special Collections, Bridwell Library, Perkins School of Theology, Southern Methodist University, http://www.flickr.com/photos/bridwelllibrary/
NDSU Libraries' Germans from Russia Heritage Collection: http://www.flickr.com/photos/ndsu-libraries-grhc/collections/
Library of Virginia: https://www.flickr.com/photos/library_of_virginia/
Center for Jewish History https://www.flickr.com/photos/center_for_jewish_history/
University of Maryland-College Park, Special Collections and University Archives, https://www.flickr.com/photos/digitalcollectionsum/
Wake Forest University Special Collections & Archives, https://www.flickr.com/photos/zsrspecial
Special Collections Research Center, George Washington University: https://www.flickr.com/photos/gwgelmansprc/sets/with/72157624837951093
CUL Digital Collections, Southern Methodist University: https://www.flickr.com/photos/smu_cul_digitalcollections