Runestone Interactive is the home for several projects that provide interactive textbooks for computer science. We currently have two books in use for our Introductory Computer Science classes. You can link to them from the library on the right.
In addition to the books we are also have a set of tools for creating interactive eBooks. The tools as well as the book are open source and available for you to use. If you do use the tools to create a book let us know and we'll add a link.