A free app that will allow students to create books that contain text, images, videos, links and audio. This app is EXTREMELY easy to use and there is even a short tutorial to get you started. When the books are complete, they can be emailed as an epub file (readable in iBooks) or a pdf, or shared through edmodo, or several other apps. If you want a book with a lot of interactive features and advanced formatting, I would use iBooks on the Mac. But for simple books with simple layouts, this is great.
The free app will allow students to create one book. If you'd like to use it in class, please let me know, because if more than one teacher wants to use it, we will need to purchase the full version for those students.