NovaScriber - A most awesome tool to write novels
StoryMill - Developers and publishers of Mac, Win, and iOS productivity, home and office and writing software such as MacGourmet, Paperless and many more. Based in MN.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
BlankPage - Stay motivated to write, and finish your story
SceneOne.app - Book writing software that runs in any browser. It is designed by novelists to have the tools and workflows they need yet be simple to use, and runs on every device (Windows, Mac, iPad, phones, etc).
Manuskript - Open-source tool for writers.