Digital Public Library of America (DPLA): collection of cultural heritage resources. Includes photographs, videos, sounds, maps, news footage, oral histories, personal letters, art, government documents.
Hathi Trust Digital Library: collection of public domain and in-copyright content from multiple sources, including Google, the Internet Archive, Microsoft, and academic library institutions.
Internet Archive: collection of over 20,000,000 downloadable e-books and texts. More available with a free archive.org account. Includes fiction, popular books, children's books, historical texts, and academic books.
JSTOR: collection of e-books and e-journals from university presses including Cornell University Press, De Gruyter, and University of California Press.