XEmacs (formerly known as Lucid Emacs) is a powerful, extensible text editor with full GUI support, initially based on an early version of GNU Emacs 19 from the Free Software Foundation and since kept up to ate with recent versions of that product. XEmacs stems from a collaboration of Lucid, Inc. with Sun Microsystems, Inc. and the University of Illinois with additional support having been provided by Amdahl Corporation, INS Engineering Corporation, and a huge amount of volunteer effort.
Darius Tools is a collection of miscellaneous scripts which are useful for a variety of purposes. They are all designed to be faster and easier to use than the command line that would normally be required to accomplish the same task. For example, there are scripts for mass conversion of WAV files to Ogg files and Ogg files to WAV files, for converting LaTeX to PostScript and viewing the output in ggv, for creating image thumbnails, for converting from the Euro to another currency, for automated updating via FTP and for removing backups recursively. The Darius Tools are split among several packages according to different categories.
The Autotoolset package complements the GNU build system by providing automatic generation of legal notices, automatic generation of GNITS-standard directory trees, a rudimentary portability framework for C++ programs, support for writing portable software that uses both Fortran and C++, additional support for writing software documentation in Texinfo and LaTeX, and a manual introducing both Autotools and the GNU build system in a unified task-oriented manner.
mu is a collection of utilities for maildirs, in particular for indexing and searching them. mu fills a database with information about your emails, which can then be queried using an easy query language. It can work stand-alone or be integrated with a mail client. It also provides an emacs-based email client ("mu4e") and bindings for Guile/Scheme.