During the most excellent writing meetup on Sunday there was a discussion of creating ebooks (as well as a discussion for creating physical books - which would be AWESOME!)

Here's some links to apps that help author ebooks.

http://demibooks.com/composer/
http://www.coronalabs.com/i-want-to-build/ebooks-comics/
http://www.redjumper.net/bookcreator/

on the Mac there is iBooks Author: http://www.apple.com/ibooks-author/

and here's a list of more ebooks authoring apps:
http://www.educatorstechnology.com/2012/10/excellent-ipad-apps-to-create-ebooks.html

Writers, start your creative engines!

cheers,
ray