Storyist is a novel and screen playing writing software for Mac OS. It can create Kindle ebooks and publish them on Amazon.com. It is also available as iPad version that supports Dropbox sync.
Michael Niemann gave Storyist 4 points out of 5 in his review. The strength of Storyist, according to the review, is the ability to add detailed information for every component of your novel or move script such as character, setting, and plot.