The Internet Archive, a 501(c)(3) non-profit, is building a digital library of Internet sites and other cultural artifacts in digital form. Here you can find numerous free-access materials produced in or related to the Soviet Union, including tons of English-language files.
Open-access digital collections of Harvard Library, containing many digitized books, periodicals, maps, archival documents, photographs, and other types of primary source materials for researching Soviet history in various languages.