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.
prerex is an interactive (command-line) editor and a LaTeX macro support package that can be used to create very attractive and readable prerequisite charts. A graphical front-end for the editor also provides a prerex-enabled PDF viewer. A prerequisite chart is a network of course boxes linked by prerequisite and co-requisite arrows.