Omega Project [This link generated an error during the last automatic check]
Omega is an extension of TeX developed by John Plaice and Yannis Haralambous. Its first release, aims primarily at improving TeX's multilingual abilities.
http://omega.cse.unsw.edu.au:8080/index.html

SC UniPad
SC UniPad is a Unicode plain text editor for the Windows NT/2000/9x/ME and XP operating systems.
http://www.unipad.org

Simredo
Free Java Unicode editor by Cleve Indriko with special features for Esperanto and right-to-left languages.
http://purl.oclc.org/net/klivo/simredoeng

VietPad: Cross-platform Vietnamese Unicode Text Editor
A Java-based Vietnamese Unicode text editor. Open, edit, convert, print, and save Vietnamese text-based files in Unicode UTF-8 format.
http://vietpad.sourceforge.net