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.
Eleven is a programming language for creating robust, scalable Web applications quickly and easily. It offers a 20x programmer productivity increase over traditional server programming languages like ASP, PHP, and JSP by automating state management and taking control of the application's look and feel. From high-level source code with a simple, C-like syntax, the compiler generates complete, ready-to-run implementations in PHP or mod_perl. Applications maintain their state in a relational database and are inherently fault-tolerant, secure, and scalable.
FramerD is a semi-structured object database integrated with a Scheme-based scripting language which supports multi-lingual programming (with pervasive Unicode), a stable module system for programming in the large, distributed applications (via an extensible RPC protocol), non-deterministic (PROLOG-like) evaluation for search and set operations, multi-threaded program execution, extensive tools for text and language analysis, built-in HTML/XML/MIME parsers, and intuitive (CGI- and FastCGI-based) Web scripting. The built-in object database robustly supports millions of objects and indexed access to those objects, both through disk files and networked servers.
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.
Geiser is a generic Emacs/Scheme interaction mode, featuring an enhanced REPL and a set of minor modes that improve Emacs' basic major mode for Scheme. The main features provided are evaluation of forms in the namespace of the current module, macro expansion, loading of files and modules, namespace-aware identifier completion, automatic documentation, jumping to the definition of an identifier, access to documentation, listings of identifiers exported by a given module, and rudimentary support for debugging. Geiser supports Guile and Racket.
Halyard is a scriptable multimedia engine with support for video, audio, graphics, and user interaction. It currently runs on Windows, and has a preliminary Macintosh port. It is based on PLT Scheme, wxWidgets, and the Quake 2 Engine. It includes a rudimentary IDE based on Scintilla.
Meep is a free finite-difference time-domain (FDTD) simulation software package to model electromagnetic systems. It supports distributed-memory parallel simulations, nonlinear, anisotropic, and dispersive media, PML absorbing boundaries, and 1D/2D/3D and cylindrical problems. It is completely scriptable from either C++ or a Scheme (GNU Guile) interface.
RScheme is an object-oriented, extended Scheme implementation with a compiler that targets C or (RScheme's own) bytecodes. It has features expected from a modern language: an object system, reflection, modules, namespaces, safe macros, threads, a system call interface (including sockets), separate compilation, and persistence, as well as the formal basis and power of the Scheme programming language. RScheme also features a powerful, elegant foreign code interface.