Yudit1 is an Open Source Unicode text editor written by Gaspar Sinai. Gaspar had wanted to be able to write Hungarian and Japanese in a single document. He realized that without much additional work, he could create a general Unicode text editor. Yudit can be used under any locale setting. It can even be used on the various free BSD operating systems, like OpenBSD which currently lacks an NLS implementation (A group of Japanese developers has started the Citrus2 project to create a complete POSIX NLS implementation with locale/iconv and a non-GPL gettext for the *BSD OSes, but I don't think anything is actually available yet).
Yudit is easy to compile (only dependent on X11 libraries), extremely easy to use, and comes with a huge set of keyboard maps. The program even comes with handwriting recognition for Chinese Hanzi and Japanese Kanji (This is a very nice touch, although in actual practice it is much faster to use an external input method engine for CJK text).
In addition, the distribution includes two indispensible utilities: uniprint, which provides Postscript-based printing of your Unicode text, and uniconv, which seamlessly converts files between a large number of Unicode and legacy ISO and national encoding formats.
Yudit is now also available for use on Windows too.
1. Yudit, http://www.yudit.org.
2. Citrus Project, http://people.freebsd.org/~imp/index-en.html.