Voice of the Shuttle is a comprehensive database of sources. While some of the more popular sources are listed here, you can search the Voice for any topic you could be working on.
Voice of the Shuttle emphasizes both primary and secondary resources, and defines its audience as people who have something to learn from a higher-education, professional approach to the humanities.
Modern American Poetry Site includes criticism, excerpts from previously published analyses of poems, biographical information, relevant illustrations, and more.
The ipl2 Literary Criticism Collection contains critical and biographical websites about authors and their works that can be browsed by author, by title, or by nationality and literary period.
Bloom's Literature Reference Center examines great writers, important works, memorable characters, and influential movements and events in world literature.
Offers scanned images of journal issues and pages as they were originally designed, printed, and illustrated (PDF files). JSTOR covers a vast area of disciplines, including literature, science, history, foreign languages, and education.