TextFlow makes it easy to review document versions simultaneously, and rapidly produce a final draft. Cut time with the only visual version manager that helps you compare, recombine and merge several versions of a document.
Purpose: Version Management. (Document Comparison).
Operating System: Desktop version under development. Online version is called CompareMyDocs.com. API available for developers.
Price: Personal and commercial editions – The online version is free. 
Development: Nordic River Software AB, Based in Umea, Sweden.
Links:
Introducing TextFlow: flash video – flash animation
Press:
TechCrunch: TextFlow’s Shiny Document Collaboration System
WordsWare blogposts:
textflow-online-is-called-comparemydocs.com
Vim is a highly configurable text editor built to enable efficient text editing. It is an improved version of the vi editor distributed with most UNIX systems.
.Link
Purpose: Text editor

The Vim Editor
Operating system: Windows, Linux, Mac e.a.
Price: Free Open Source “charity-ware”, ie you are encouraged to make a donation to orphans in Uganda
Development: Open Source, copyright Bram Moolenaar (bram@vim.org)
Links:
WordsWare blogposts:

GVim Editor - a graphical version.
Vim -the keyboard text editor.
Other related posts, tips and tutorials:
PyRoom is a free editor that stays out your way – and keeps other things out of your way, too. As a fullscreen editor without buttons, widgets, formatting options, menus and with only the minimum of required dialog windows, it doesn’t have any distractions and lets you focus on writing and only writing.
Purpose: Full Screen Text editor
Operating system: Linux (Windows version is in the make)
Price: Free under the GNU General Public License.
Development: The PyRoom Team
Links:
WordsWare blogposts:
-
Other related posts, tips and tutorials:
AbiWord is a free word processing program similar to Microsoft® Word. It is suitable for a wide variety of word processing tasks.
Purpose: Word Processing
Operating system: Linux – Windows -Mac – QNX
Price: Free under the GNU General Public License.
Development: AbiWord Development
Links:
WordsWare blogposts:
Yalm Magazine Compared Abiword with OpenOffice.org Writer
Other related posts, tips and tutorials:
Red Hat Magazine -AbiWord Team interview
AbiWord Portable from PortableApps (Windows)
RedNotebook is a graphical diary and journal helping you keep track of notes and thoughts. It includes a calendar navigation, customizable templates, export functionality and word clouds. You can also format, tag and search your entries.
Purpose: Journaling
Operating system: Linux – Windows
Price: Free – Open Source under the terms of the GNU General Public License

Development: Jendrik Seipp
Links:
WordsWare blogposts:
Other related posts, tips and tutorials: