Ecasound is a software package designed for multitrack audio processing. It can be used for simple tasks like audio playback, recording, and format conversions, as well as for multitrack effect processing, mixing, recording and signal recycling. It supports a wide range of audio inputs, outputs, and effect algorithms. Effects and audio objects can be combined in various ways, and their parameters can be controlled by operator objects like oscillators and MIDI-CCs. A versatile console-mode user interface is included in the package.
ECB is a source code browser for (x)emacs. It displays a couple of windows that can be used to browse directories, files, and file contents like methods and variables. It supports source code parsing for languages like Java, C, C++, Elisp, Scheme, Perl, TeX, LaTeX, etc. In addition, it offers an (optional) permanent "compile window" at the bottom of the emacs frame, which is used to display all help and compile output. The rest of the frame is called the "edit area", which can be divided into several edit windows that are used for editing the sources. Deleting some of the edit windows neither destroys the compile window nor the browsing windows. It requires the CEDET suite.
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.