I'm pleased to announce Jutoh, an ebook creator with WYSIWYG editing, that can generate Epub, Mobipocket, ODT and plain text. Do head over to www.jutoh.com and give it a whirl. We've got a special introductory offer (not that it's going to be expensive anyway!)
How does Jutoh differ from eCub? eCub is good for when your ebook content has already been written and you don't want to do too much editing. Jutoh is better for the less technical user who wants word processor-style editing, and needs to import from a wider variety of sources, such as a single word processor file (eCub requires you to break the book into pieces manually whereas Jutoh helps you split a file into chapters).
You don't have to deal with XHTML in Jutoh if you need to add formatting. Jutoh is somewhat more polished and more fun to work with, and has various extras such as a desktop for adding shortcuts and notes, the ability to add scraps (web addresses, images, and text) to your Jutoh document without them appearing in the ebook, and several ways to customize your book for different web sites or publishers.
There are lots of other features that you can read about at www.jutoh.com and try by downloading the demo. Jutoh works on Windows, Mac, Linux, FreeBSD and Solaris x86 and is portable between machines using its own USB drive installation or the Jutoh PortableApps.com installer.
If you have ideas for improvements, or find any problems, do let me know what you think.