Storyist - A powerful writing environment for novelists and screenwriters.
Apple iWork - iWork is an office suite by Apple.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
Airborn - Create and edit documents online without sacrificing your privacy
MakeStoryBoard - MakeStoryboard is simple online storyboarding software that helps thousands of users fast and easy visualize their stories.
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.