Larceny is a simple and efficient implementation of the Scheme programming language. Created originally as a test vehicle for research on garbage collection and compiler optimizations, Larceny has grown into a major multi-platform system, and is one of the very few implementations that support all four de facto standards for Scheme: IEEE/ANSI, R5RS, ERR5RS, and the R6RS. Development of Larceny has been supported by NSF, Sun Microsystems, and Microsoft.
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.
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.
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.
eINIT is an alternative init system. It's quite fast, since it can potentially be used without the help of any scripting at all, but it is still flexible and extremely modular. The focus is on speed and parallelisation, mostly with embedded devices and low-downtime servers in mind, and benchmarks do suggest that it's doing a fairly good job at that. It compiles cleanly (and should thus work, provided someone writes appropriate modules) on Linux, FreeBSD, and Darwin/Mac OS X.
TwistedWave is a very easy-to-use and powerful audio editor. It supports Audio Unit plug-ins and many file formats, including wav, aiff, caf, mp3, mp4, FLAC, and Ogg Vorbis. It has good multichannel support, so you can apply Audio Units to a selection of channels. It supports unlimited undo and redo, which work instantly. Zooming in and moving around the waveform is very fast, even with very large files. All the effects are applied in the background, saving a lot of time.
Sepp is a version of the classic sliding puzzle game in which the properly ordered tiles form a picture. The picture is user-selectable, as is the tile-grid geometry. Additionally, Sepp implements an innovative kind of player aggravation: based on a user-configurable degree of evil, it decides, during each animation frame, whether it will disturb a tile while the game is in progress. Sepp is written for the DrScheme enviroment, which is available for all major platforms.
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.
Roadsend PHP produces optimized stand alone applications, libraries, and Web applications from standard PHP source code. The compiler produces native machine code, not PHP byte code, so no interpreter is required. It is a new implementation of the PHP language and runtime environment compatible with Zend PHP. It does not share any code with the original PHP implementation.