Litcharts is a site that provides free summaries and analyses of literary works. It is similar to Sparknotes or Cliff Notes, but free.
Students, or teachers, can view them online, download a PDF file, or view them through an iPhone app. (Don't have an iPhone, don't worry- most smartphones can view PDF files, so just download the files to your smartphone.)
I read through a few and found them to be well done and easy to use. They don't have a huge library yet (I counted 39 titles today), but they have the classics and most commonly assigned books and news ones are in the works.