Most search engines have a filter for finding images free of most copyright restrictions (yes, even Google Images!). The following websites have collections of images that are openly licensed specifically for reuse or are in the public domain.
Grove Music Online comprises the full text of The New Grove Dictionary of Music and Musicians, 2nd ed., edited by Stanley Sadie and John Tyrrell (London, 2001), The New Grove Dictionary of Opera, edited by Stanley Sadie (London, 1992), and The New Grove Dictionary of Jazz, second edition, edited by Barry Kernfeld (London, 2002). Articles that have been updated since their appearance in print are date-stamped in the upper right corner of the screen.
The Music Index Online is the single most comprehensive guide to music periodical literature. The coverage spans from 1973 to the present and contains citations from over 850 music periodicals published in 40 countries.
Kanopy is a streaming video service that offers international films and documentaries across diverse subjects and disciplines. Collections include titles from the DEFA Film Library, ArtMattan Films, HBO, PBS, Frameline, Ruscico, Pragda, BBC, Flicker Alley, National Film Board of Canada, First Run Features, Cinema Libre Studio, New Day Films, and the Criterion Collection/Janus Films.
Art & Architecture Complete provides full-text coverage of 380 periodicals and more than 220 books. In addition, this database offers cover-to-cover indexing and abstracts for more than 780 academic journals, magazines and trade publications, as well as for over 230 books. Art & Architecture Complete also provides selective coverage for 70 additional publications and an Image Collection of over 63,000 images provided by Picture Desk and others.
The full contents of Vogue magazine (US edition) in full color page image, from the first issue in 1892 to the present, with monthly updates for new issues.