Zoho - http://www.zoho.com
Zoho.com offers a comprehensive suite of award-winning on-line business, productivity & collaboration applications. Customers use Zoho Applications to run their business processes, manage their information and be more productive while at the office or on the go, without having to worry about expensive or outdated hardware or software.
Shutterborg - http://shutterb.org
Shutterborg is a free word processor that runs entirely in your web browser. Instead of using expensive desktop software, Shutterborg makes life easy by allowing you to edit documents online for free. It's easy to get started - just click an option from the list on the right.
gOffice - http://www.gOffice.com
gOffice Web Word Wizard is a wrapper around Microsoft Word 2007. This means you can implement a subset of the features found in Word on your website. The output quality of the files will be outstanding because the files will be true Word files. Microsoft publishes written instructions in their developer knowledge base on how to run Word on a web server, but they caution against doing so. Microsoft also distributes free code to allow you to write current Word documents directly using Microsoft Visual Studio based code, without involving Word itself. Microsoft wants the Word format to endure and be used.
Google - http://www.google.com
Create new documents or access your documents, anytime. All your documents are automatically saved and stored in Google Drive. Access them wherever you go, from any device. Plus, you can open and edit other file types without any special software.