CyberUnits is a cross-platform class library for rapid development of high-performance computer simulations in life sciences. It supports modelling for biomedical cybernetics and systems biology with Object Pascal.
GeoGebra is free and multi-platform dynamic mathematics software for learning and teaching geometry, algebra, statistics, and calculus. Download the free software at http://www.geogebra.org. Find the sourcecode at http://www.geogebra.org/trac
VisualPetri is Petri net editor for Windows platform based on GDI Plus library with an integrated simulator. Note: a Petri net is one of several mathematical representations of discrete distributed systems.