General Digital Collections 
Making of America Website (Cornell University)
Making of America Website (University of Michigan)
Documenting the American South

Museums (including online exhibits)
Peabody Essex Museum
New Bedford Whaling Museum
Mystic Seaport: The Museum of America and the Sea
Metropolitan Museum Collection of American Art
Smithsonian Museum
Matthew Brady's Portraits at the National Portrait Gallery
The Philadelphia Museum of Art
World's Columbian Exhibition of 1893
American Studies at the University of Virginia

Organizations
American Literature Association
South Atlantic Modern Language Association
American Humor Studies Association
Modern Language Association
Society for the Study of American Women Writers

Author Societies/Movements/Texts
James Fenimore Cooper Society
Edgar Allan Poe Society of Baltimore
The Museum of Edgar Allan Poe -- Richmond
American Transcendentalism -- VCU website
Ralph Waldo Emerson Society
The Thoreau Society
Nathaniel Hawthorne Society
The Melville Society
The Stowe Society
Uncle Tom's Cabin and American Culture website (Stephen Railton)
Harriet Wilson Project
William Dean Howells Society
Henry James Society
Mark Twain Circle of America
Adventures of Huckleberry Finn  (UVA)
The Walt Whitman Archive 
The "Vault at Pfaff's"
Emily Dickinson International Society
Emily Dickinson Electronic Archive
Stephen Crane Society
Kate Chopin Society
Jack London and Jack London Online
Charles Chesnutt Digital Archive
Charlotte Perkins Gilman Society
Frank Norris Society
International Dreiser Society and Dreiser WebSource
Edith Wharton Society
F. Scott Fitzgerald Society Home & News
Ernest Hemingway Society
William Faulkner Society
Robert Penn Warren Circle
Toni Morrison Society

Timelines/Author Information/Literary Movements
Donna Campbell's Web Resources (linked with permission)

General Writing Information
The Writing Center at Winthrop University
OWL at Purdue University