History:

• Archaic Wonder Tumblr (Ancient & Medieval)
• Archive.org
• Blvck Archives (curated by Renata Cherlise)
• David Wojnarowicz Papers (Fales Library)
• DigiBaeck: German-Jewish History Online (Leo Baeck Institute)
• Founders Online (correspondence and other writings of six major shapers of the United States)
• French Revolution Digital Archives (Stanford)
• National Archives UK Flickr
• National Library of Ireland Flickr
• Outhistory.org - Gay History in Nevada & Las Vegas
• Outhistory.org - The Lesbian Herstory Archives Button Collection
• Pop History Dig
• Virtual Vietnam Veterans Wall of Faces
• White Rose documents (leaflets pertaining to the White Rose anti-fascist movement)
• Women’s Museum of Ireland (online only)

American History:

• Alice Marshall Women’s History Collection (PennState University) (advertising, trade cards from 1900s)
• American President (UVA)
• Colonial North American Project (Harvard University)
• Digital History
• Discovering American Women’s History Online (MTSU)
• Historic American Buildings Survey (LoC)
• Iowa Women’s Archives Tumblr
• Making Of America (UMich)
• The American Presidency Project (UCSB)
• UISpecColl Tumblr
• What America Ate (food archives, Dr. Helen Veit)

Russian History:

• Collection of Russian & Ukrainian Posters, 1917-1921 (NYPL)
• House of Romanov (Interactive Family Tree) (must translate)
• Resources of Other Collections Relating To Russian History (BYU)
• Russian Posters Collection, 1919-1989 & Undated (Duke University)
• Russian Presidential Library Collection (must translate)
• Soviet History (MSU)
• Soviet Postcards Tumblr
• Stalinka (images etc relating to Stalinism - University of Pittsburg)

Maps:

• Global Middle Ages
• NYPL Map Warper (a tool for digitally aligning ("rectifying") historical maps from the NYPL's collections to match today's precise maps.)
• Panoramic Maps collection (LoC)

Greek mythology and archaeology:

• Perseus (Tufts University)
• Theoi Greek Mythology

Literature:

• comic book master post on livejournal
• comic book master post on tumblr
• Emily Dickinson Archive
• Zora Neale Hurston papers (UF)

Fashion/Beauty:

• Avon Digital History Archive (historical documents of Avon company)
• Cosmetics & Skin
• Fuck Yeah Nostalgic Beauty Tumblr
• Just Seventeen Tumblr

Miscellaneous:

• Atlas Obscura
• Busy Beaver Button Company Archives (amazing button/pin collection)
• Calisphere (digital collections all over California)
• HEARTH: Home Economics Archives (Cornell)
• JSTOR
• Library of Congress
• New York Heritage (connects you to a variety of digital collections from all over New York State)
• New York Public Library Online Picture Collection
• Setlist Wiki (for concerts)
• The Black Vault (case files and declassified files from the United States government)
• The Internet Archive - a non-profit, is building a digital library of internet sites and other cultural artifacts in digital form
• World Digital Library
• Wreck Site (database of wreckage sites all over the world)