Project Bartleby
http://www.bartleby.com
Free access to thousands of public domain works, from Sophocles to H.G. Wells, including lots of poetry.

The EServer
http://eserver.org
Formerly called the English Server, this collection now includes works on a range of subjects. Housed at the University of Washington. The collection includes over 30,000 titles.

Voice of the Shuttle
http://vos.ucsb.edu
Site devoted to humanities research. Includes links to information on classical studies, cultural studies, cyberculture, linguistics, world and English literature, literary theory, philosophy, minority and women's studies, and much more.