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 Kawa Scheme System is a full Scheme implementation, completely written in Java. Scheme functions and files are automatically compiled into Java byte-codes. Kawa does some optimizations, and the compiled code runs at a reasonable speed. It provides the usual read-eval-print loop, as well as batch modes. The Kawa compilation framework is also useful for implementing other languages on top of JVM. There is active development of XQuery (the XML query language), and less active development of Emacs Lisp, Common Lisp, and EcmaScript.
BHL is an Emacs mode which enables you to convert plain text files into HTML, LaTeX, Texinfo, SGML (Linuxdoc), and TXT files. The BHL mode handles three levels of sections, many sectioning styles, common font-styles, any kind of lists, tables, URLs, horizontal rules, and Wiki names. BHL handles a list of links (lol) and a table of contents (toc): you can browse the lol and the toc, insert them where you want, and update the sections' numbers with one keystroke.