ArgoUML is a pure Java open source UML CASE tool that provides cognitive support for object-oriented design. ArgoUML provides some of the same editing and code generation features of a commercial CASE tool, but it focuses on features that enhance usability and support the cognitive needs of designers. Uses XML file formats: XMI and PGML.
Cooledit is a text editor for the X Window System. It contains a built-in Python interpreter for macro programming, and it includes a rich set of utilities and features. It has multiple edit windows and a beautiful, intuitive user interface that requires no tutoring to learn to use. It can be used as a programmer's IDE and has syntax highlighting for a large number of programming languages. It contains an interactive graphical debugger for C/C++ programs.
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.
jake (Jointly Administered Knowledge Environment) is a reference source which makes finding, managing, and linking online journals and journal articles easier for students, researchers, and librarians. jake does this by managing online resource metadata with a database union list, title authority control, linking tools, and a local holdings layer.
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.
make_faq is an HTML generator that builds chunks/chapters/questions-and-answers or whatever, and builds indexes to hold it all together. It's a fairly general purpose tool for creating a set of indexed pages, but it's common usage is to build FAQ (Frequently Asked Questions) HTML from text documents. See the examples for a better understanding.
The ManEdit UNIX Manual Page Editor is an editor specifically tailored for UNIX manual pages. It has a preview viewer, uses the manual page XML format for easy editing, and comes with a tutorial and reference guide. It uses the GTK+ widget set and features syntax highlighting, a complete drag and drop system for easy viewing and editing, a crash recovery system, and sample manual page templates.
Rute (Rute Users Tutorial and Exposition) is a book on GNU/Linux that aims to be the definitive guide for new users as well as sufficing as training course material, covering both the RHCE and LPI requirements. It covers essential theory to UNIX as well as giving practical tutorials on all fundamental aspects of Unix administration, from basic commands, the theory of TCP/IP, the Linux filesystem, through to configuration of mail, DNS, and other servers, through hardware configuration and package management. It is not Unix-specific but tends to give examples suited to Debian and RedHat-like systems. Rute comes in HTML and PDF formats.