National Academy Press Reading Room - 1000+ books , free for the reading, first page to last. Available in a variety of versions, including scanned pages in image format, hypertext HTML books, and as Adobe Acrobat PDF files.
netLibrary - 'The World's Largest Collection of Electronic Books."
Spark Notes - Created by Harvard University students and alumni, SparkNotes is a collection of free online study guides to approximately 100 literature classics. Each SparkNote contains sections on context, characters, overall summary, chapter-by-chapter summary and commentary, study questions, and a message board for collaborative learning.