iBooks Author - iBooks Author, free from the Mac App store, allows you to create beautiful Multi-Touch textbooks — and just about any other kind of book.
Issuu - Issuu is the leading digital publishing platform delivering exceptional reading experiences of magazines, catalogs, and newspapers.
Atavist - Atavist provides a suite of publishing tools to tell stories and build websites.
Scribd - Unlimited books, audiobooks & comics. Unparalleled discovery. Any device. $8.99/month
Mobipocket eBook Creator - Mobipocket eBook Creator is one of the easiest way to create a professional level of eBooks by simply providing some HTML and image files to your publication.
Magzter - Magzter is the world's largest digital magazine newsstand with over 10,000+ magazines in its catalogue. Read them anytime and anywhere on iPad, iPhone, Android devices and the web.