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.
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.
TeXtrace is a collection of scripts that convert any TeX font into a Type1 .pfb outline font immediately suitable for use with dvips, pdftex, Acroread, and many other programs. The main advantage of using Type1 fonts with TeX is that Acroread renders TeX's bitmap fonts ugly on screen, but it renders outline fonts beutifully and fast.
JasperAssistant is a visual report designer tool for JasperReports, a popular open-source reporting engine. It is built on top of the Eclipse's plug-in architecture, and its main goal is to help you create JasperReports report definition files through an intuitive graphical interface.