Apple provides an excellent e-book publishing tool—iBooks Author, available free via the Mac App Store, a tool that makes writing interactive e-books for iPad a breeze.
The current Version 2.0 of iBooks Author supports the following features:
Multi-Touch books
Interactive images and video support
3D support
Custom HTML widgets
Export to PDF
Custom fonts support
Mathematical expressions support
Retina display support
Drag-and-drop content support
Templates for common book formats—cookbooks, photo books, and so on
Publishing books to iBookstore from within iBooks Author
You need an iPad to test/preview your books on the iPad, so make sure you accessorize yourself with one.