The LitCharts Library provides chapter summaries to some of the most frequently read books in high school English curricula. It also features an iPhone App for reading. Teachers should be aware of this site as it bills itself as "the faster, downloadable alternative to SparkNotes."
This is a great article about the evolution of reading. Given the influx of iPads and eReaders into classrooms, the concept of "books" is certainly changing.
This app is free until April, though know that some content becomes an in-app purchase. Bookabi allows students to create their own storybooks with 2D and 3D characters. They can upload their own photos and pictures plus save and share their final projects.