LyX is a document processor that encourages an approach to writing based on the structure of your documents, not their appearance. It is intended for people people who write and want their writing to look great without tinkering with formatting details, font attributes, or page boundaries. On screen, it looks like any word processor, but it uses the TeX engine for printed output and producing richly cross-referenced PDFs. It is stable and fully featured.
SGMLtools-Lite is the successor of SGMLtools. It is a set of Python and DSSSL scripts which makes interaction with Jade in order to process (mostly DocBook) SGML files a breeze, and is easy to extend with custom processing instructions. Out of the box, SGMLtools-Lite knows how to convert DocBook to HTML (2 styles), JadeTeX, DVI, RTF, PS, PDF, plain text, and PalmOS iSilo format. It also comes with a conversion script to convert "old" LinuxDoc documents to DocBook.
wxDesigner is a dialog editor and RAD tool for the wxWindows C++ library and its popular Python and Perl bindings. It includes a visual dialog editor, a bitmap editor, a syntax-highlighting source editor, and built-in mechanisms for automatic generation of file skeletons, GUI classes, event handlers, and getter functions. It provides an identical user interface and identical functionality for C++, Perl, and Python, and it can generate output in C++, Python, Perl, and XML.
gtex-letter attempts to deliver an easy alternative interface to LaTeX-letter. It is heavily configurable, and it supports multiple letter headers and default letter openings (which are configurable in the rc-file). Users can choose from three different levels of graphical interface complexity. Novice is easy to understand, while expert is straight-forward. There is also a non-interactive mode that makes production of standard-letters very fast. gtex-letter is implemented in Python and based on GNOME.
This program examines the current buffer and determines the indent style in use, then sets vim tabstop/shiftwidth/etc to work correctly with that style, and creates a syntax match to highlight any indentation in the file that does not match the selected style. It can be set up to auto-detect when opening files.