The EServer
http://www.eserver.org
The Eserver (originally called the English Server) publishes original scholarly and creative works in the arts and humanities (art, architecture, drama, fiction, poetry, history, political theory, cultural studies, philosophy, women's studies, and music). Their collection also includes many classic texts as well as scholarly journals useful for research. Currently includes 30,393 documents.

The On-Line Books Page at the Penn Library
http://digital.library.upenn.edu/books
This section of the Penn University Library is an index of on-line books available around the Web. Browse by author, title, or subject. Also includes links to serial archives.

Literature.org
http://www.literature.org
Classic texts in HTML format.

Alex Catalogue of Electronic Texts
http://www.infomotions.com/alex
Public domain texts. American and English literature and Western philosophy.

Bibliomania
http://www.bibliomania.com
World literature. Over 8,000 classic texts.

Project Gutenberg
http://promo.net/pg
The oldest and the biggest repository of on-line public domain texts. The site is searchable, with full bibliographic data returned. Titles are downloadable in "plain-vanilla ASCI" format.