Yet Another Dynamic Engine (YADE) is an extensible framework that is designed with dynamic libraries in a way that it is easy to add new numerical models and objects. There are four different models: Discrete Element Method based on spheres, a second method based on tetrahedra, modelling with lattice elements, and Finite Element Method.
Zeobuilder is a user-friendly GUI toolkit for the construction of advanced molecular models. It is extensible via a plugin framework and contains several advanced tools for building, aligning, manipulating, and analyzing molecular structures. It describes a molecular model with a hierarchical data-structure of reference frames. This facilitates operations on models at different levels of detail.
bcr harms takes a model of the quantum harmonic oscillator and adapts it as a soft synth. It lets you hear and see how the oscillator wave functions evolve in real-time as you modify amplitudes and other parameters. The user interface is based on and integrates with the BCR2000 MIDI controller, but the application can be used without a controller.
ePeriodique is a graphical application which displays the periodic table of the elements. It shows basic data for each element, pictures, Bohr models, and lattice structures. It tries to use the EFL way and provide two themes, one for the desktop (default) and one for small displays (small).