Here are some links to websites related to systems thinking and dynamic modeling:

High Performance Systems
http://www.hps-inc.com

Mohaseboon
http://www.mohasboon.com/SystDyn.htm

Vensim
http://www.vensim.com

An Intro to Modeling and Simulations
http://www.outsights.com/systems/modsim/modsim.htm

Arizona State University
http://www.public.asu.edu/~kirkwood/sysdyn/SDRes.htm

Profit Patterns
http://www.profitpatterns.com/patterns/patterns.html