Apple iWork - iWork is an office suite by Apple.
Novelize - Novelize is an online novel writing app designed to keep authors on track.
Airborn - Create and edit documents online without sacrificing your privacy
Manuskript - Open-source tool for writers.
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.
BlankPage - Stay motivated to write, and finish your story