Schemik is a high-level lexically-scoped implicitly-parallel dialect of Scheme and Common LISP. This means the parallel execution of programs is done independently of the programmer, and each program written in Schemik always produces the same results no matter which parts of the program are executed simultaneously.
GNU dico is a flexible dictionary server with a set of accompanying utilities. It supports a wide variety of dictionary database formats, ranging from the traditional "dict.org" databases up to Wikipedia format. Support for arbitrary new formats can be easily added using loadable modules. The dico library provides an API for writing new modules in C, Guile, or Python.
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.
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.
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.
Industria is a collection of portable R6RS Scheme libraries for cryptography (AES, DES, Blowfish, HMAC, MD5, SHA-1, SHA-2, RSA, DSA, etc.), zip/gzip/zlib decompression, disassembly of amd64 machine code, Off-The-Record messaging, bytevector pack/unpack syntax, TLS connections via custom binary ports, and more.