AFI Catalog of Feature Films - From the American Film Institute, this catalog has comprehensive information and history for films created from 1893-1993 and less detailed information available for films released after 1993.
National Film Preservation Board - The National Film Registry, from the Library of Congress, includes both overviews and in-depth essays on most of the titles on the Registry. It also includes links to resources on topics such as copyright and film (under "Resources").
MoMA Learning: Film - This resource from the Museum of Modern Art is divided into four sections: Advent of Cinema; Experimentation with Sound; Documentary and Propaganda; and Experimentation in Film/the Avant-Garde. Clicking on the images takes you to a summation of each film.
Jump Cut - This online, open access journal covers virtually all aspects of film studies, from classics to contemporary works.
Women Film Pioneers Project - This site represents over 290 women who worked on silent films as directors, producers, screenwriters, editors, and more.
The Interviews: An Oral History of Television! - From the Television Academy Foundation, this site features over 900 first-person interviews with people involved in the birth and growth of the American television industry, ranging from Ru Paul to Betty White to Quincy Jones.
AdViews - This collection from Duke University features historic commercials from the 1950s-1980s; videos are viewable on iTunes or Internet Archives.
National Screening Room - Useful for understanding attitudes in the early 20th century as well as film history, National Screening Room features downloadable early movies, from short feature films to advertising to propaganda and politics.