ALA (American Library Association): Libraries and the Internet Toolkit
According to ALA, "open access refers to the free and open availability of scholarly content on the Internet. Open-access materials are made available via digital repositories (archives) or scholarly journals. Open access does not equate to 'anyone can publish anything'; rather, open access refers to the ability of anyone to view, download and use scholarly information. Though open access tends to be discussed in the context of scholarship and academic publishing, it is important to note that open access benefits everyone, not just academics. Information made available through open access is freely available to all users everywhere, with as short an embargo period as possible."
This research guide provides links to a variety of open access resources, including archives, repositories, libraries, books, textbooks, dissertations, theses, government documents, journals, newspapers, and multimedia.