Manuskript - Open-source tool for writers.
Microsoft Word - Microsoft Word is a commercial word document processor for Windows.
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.
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.
Novelize - Novelize is an online novel writing app designed to keep authors on track.
AbiWord - AbiWord is a free software word processor.