"Cornell Open is the new global open access portal for classic out-of-print titles from the distinguished catalog of Cornell University Press. Funded by the newly created Humanities Open Book Program, a collaborative effort between the National Endowment for the Humanities (NEH) and The Andrew W. Mellon Foundation, Cornell Open offers for the first time open access to key titles in literary criticism and theory, German studies, and Slavic studies."
Some of the books are also relevant for history. There are currently 20 books, selected based on their circulation numbers. The list is to be extended to 150.
Source: Cornell Open, About, http://www.cornellopen.org/