Subtext is a cool app that is currently available for iPad only and it's purpose is to provide a place for students (and teachers) to have digital book talks. Once you install this free app you can read and annotate ebooks, create questions about the books and even write blog posts as you read. As a teacher or group facilitator you can create bookshelves for your members as well as set your group as public or private.
For those schools who have deployed a 1:1 iPad solution, this would be a great tool for encouraging students to engage in meaningful discussion while reading books. The teacher could also facilitate this discussion by creating questions and highlighting content. Subtext is currently offering a contest for users who supply suggestions on how they would use this in the classroom. If selected you could win 10 iPads for your classroom.