GLAME (GNU/Linux Audio Mechanics) is meant to be the GIMP of audio processing. It is designed to be a powerful, fast, stable, and easily extensible sound editor for Linux and compatible systems. It has full support for non-destructive editing including undo/redo and applying LADSPA effects. Its supported platforms are Linux, BSD, IRIX, and OS X. It uses guile and libxml, and the GNOME libs available is highly recommended. MP3 and Ogg files can be processed if libmad and libvorbisfile are installed.
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.
MIT/GNU Scheme is an implementation of the Scheme programming language, providing an interpreter, compiler, source-code debugger, integrated Emacs-like editor, and a large runtime library. MIT/GNU Scheme is best suited to programming large applications with a rapid development cycle. Recent versions of the system are supported on the following platforms: GNU/Linux, *BSD, OS/2, and Windows.
Sizzle is a Scheme interpreter for embedding into C applications and for standalone scripting. It implements a nearly complete subset of R5RS Scheme, adding a lot of primitives for U*ix scripting, regular expression searching, a simple module system, dynamic library linking, powerful string processing procedures, and much more. It includes a user's guide and an embedding manual in texinfo format, some examples, the embedding library, and a standalone interpreter for interactive use and scripting.
STklos is a free Scheme System conforming to R5RS. The implementation is based on an ad-hoc Virtual Machine. It can also be compiled as a library, so that one can easily embed it in an application. Its features include an efficient and powerful object system based on CLOS, a simple-to-use module system, implementation of the full tower of numbers defined in R5RS, and easy connection to the GTK+ toolkit. STklos is the successor of STk, a Scheme interpreter tightly connected to the Tk toolkit.
Astwar is a ncurses based simple space shooter; two little ships (asterisks), each on one side of the screen, try to shoot each other. There is network support with several multiplayer options and user extension with Scheme (via Guile) to program the little ship to do some things automatically are in the works.
Chicken is a Scheme compiler that translates most of R5RS Scheme into relatively portable C. It supports fully general tail-call recursion, first-class continuations, and has a very flexible and efficient interface to C and C++. Chicken implements several extensions to the Scheme language: lightweight threads, pattern matching macros, dynamic loading of compiled code, and various object-oriented paradigms, such as TinyCLOS, and others. The library system includes hundreds of convenient modules for practical use.
Kipt (Kizome's ISA Piercing Tool) is an HTTP proxy server and proxying name server with the ability to forward requests to other HTTP proxies or to get the documents directly from hosts. It can go through MS ISA Server or MS Proxy doing NTLM authentication. If you're stuck behind a restrictive firewall or proxy with at least one port open for outgoing connections and you have access to a machine outside, you can have nearly full Internet access by using this proxy and the socksify program from dante.