tex-upmethodology provides a complete set of LaTeX styles that permit you to write documents according to a UP-based methodology. Its major features are document history, task management, design and specification documentation, and helping tools. tex-upmethodology is officially supported by CTAN.
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.
GNU TeXmacs is a free wysiwyw (what you see is what you want) editing platform with special features for scientists. The software aims to provide a unified and user friendly framework for editing structured documents with different types of content: text, mathematics, graphics, interactive content. TeXmacs can also be used as an interface to many external systems for computer algebra, numerical analysis, and statistics. New presentation styles can be written by the user and new features can be added to the editor using Scheme.
The goal of Hilbert II, which is in the tradition of Hilbert's program, is the creation of a system that enables a working mathematician to put theorems and proofs (in the formal language of predicate calculus) into it. These proofs are automatically verified by a proof checker. Because this system is not centrally administered and enables references to any location on the Internet, a world wide mathematical knowledge base could be built. It also contains information in "common mathematical language".
lhs2TeX is a literate programming tool. It is implemented as a preprocessor that generates LaTeX code from literate Haskell sources. It allows for and provides different styles for the formatting of code. You can easily select between representing operators with mathematical symbols or with ASCII approximations, as well as deciding whether or not to highlight keywords. The formatting of your own defined tokens may be adjusted. Preprocessor-style conditionals are supported, and Haskell can be used to generate parts of the document.
deplate converts wiki-like markup to LaTeX (standard classes, koma, dramatist, sweave), HTML/PHP (single page, chunked/website, HTML, or s5-based slideshow), DocBook (article, book, man/ref page), and really plain text. Currently supported input formats are viki and Ruby's rdoc. The viki markup supports footnotes, citations, index, table of contents, embedded LaTeX for mathematics, integration with R for dynamically generated figures and tables, and more. Output can be customized via page templates.
PyC2LaTeX converts a given C, Java, or Think/Fractal adl or idl file into a LaTeX file that can be used for pretty-printing the code. It features line numbering, indentation, support for international characters, and syntax highlighting. The text in the output is otherwise unmodified. One of the main goals of this script is to provide LaTeX code that can be directly included in other LaTeX files to write software documentation.
IDX-DocBook2LaTeX is a stylesheet which translates DocBook documents into LaTeX. It is written in Perl, using the XML::XPathScript package from AxKit. It features the ability to handle tables, indices, figures, footnotes, and more. The XSLT-like templating philosophy built into XPathScript makes it easy to extend.