ODE is a free library for simulating rigid body dynamics (e.g. ground vehicles, legged creatures, and motion in VR environments).
http://www.q12.org/ode/ode.html
Consultants in customised mathematical analysis, complex systems modelling, decision analysis and optimisation, decision support tool design and development, and spreadsheet services to researchers and managers.
http://www.woodwardresearch.co.nz/
ESSA, founded in 2002, encourages the development of social simulation in Europe and more widely, promotes international cooperation among those working in the field, and organizes regular regional and international conferences.
http://www.essa.eu.org
EconSim? is an extendable framework for Economics Simulation. It is very strongly based on the Object Oriented approach. It is profoundly extendable in Java.
http://www.econsim.co.uk
An international working group of professional simulationists and students dedicated to simulation projects, tools and methodology.
http://st.itim.unige.it/liophant/liophant.html
Simulation software to emulate products or machinery for the purpose of increasing sales, advanced service, maintenance, and training.
http://www.machinesimulation.com/
PMC is a simulation and scheduling services company with expertise in applying simulation and scheduling in manufacturing and other industries. PMC also provides technical staffing in simulation and industrial engineering as well as contract program
http://www.pmcorp.com
Open source codes demonstrate FDTD capabilities, from algorithms to memory mangagement and output visualization.
http://www1.borg.umn.edu/ToyFDTD1.html