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.
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.
Kahua is a continuation passing style (CPS) application framework and server. It is written using the Gauche implementation of Scheme. It has the advantage that you can use "continuations" easily, so you can solve the typical Web application's problem of process disconnection. It allows you to program declaratively by using S-expressions as a fundamental data type, you can use Kahua's Object Database to persist data, and you can modify the function being run, supporting incremental development.
Inlab-Scheme is an independent implementation of the algorithmic language Scheme and conforms to the R4RS and the IEEE Standard 1178. In addition to the language core, Inlab-Scheme has support for image processing which allows the implementation of OCR and image recognition applications. Inlab-Scheme comes with two built in graphic file format converters which convert the PATIMG patent file format and the ST.33 patent file format to multipage TIFF without decompressing.
GeneRecon is a software package for linkage disequilibrium mapping using coalescent theory. It is based on a Bayesian Markov-chain Monte Carlo (MCMC) method for fine-scale linkage-disequilibrium gene mapping using high-density marker maps. GeneRecon explicitly models the genealogy of a sample of the case chromosomes in the vicinity of a disease locus. Given case and control data in the form of genotype or haplotype information, it estimates a number of parameters, most importantly, the disease position.
InteLib is a library of C++ classes that lets you do Lisp/Scheme programming within your C++ programs, even without any additional preprocessing, without all those calling conventions. You can write code that is accepted by a C++ compiler while thinking in a "Lisp/Scheme mode", and the code you write will look much like Lisp/Scheme code, although it will be pure C++.