Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
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.
Manuskript - Open-source tool for writers.
Novelize - Novelize is an online novel writing app designed to keep authors on track.
Final Draft - Use your creative energy to focus on the content; let Final Draft take care of the style.
Dabble Writer - Writing software for novelists.