This site claims to be "a comprehensive guide to free book summaries, literature notes, and study guides." Books are listed alphabetically. Site also offers a few suggestions for finding other book reviews and summaries.
"Say goodbye to Cliff's Notes - FreeBooknotes.com has everything you need when it comes to book summaries and analysis - and best of all - it's free!"
[ of course, there is a lot of advertising on the page, but this is the price to pay for a free service. And when you come to the end of the page, you find a long list od book. For each, the page suggests several free online guides to help you or your students with the study of the book. Very well done and useful indeed for all those studying literature!]