2D Simulations using NetLogo:

[You need Java 1.4.1 or higher to view these simulations. This can be downloaded from here.
NetLogo can be downloaded from here.]

 

For the experience:

An applet demonstrating a simple hill-climbing algorithm.
An applet for playing with ants.
An applet demonstrating ants clustering blocks [stigmergy].
An applet demonstrating how opinions can spread [positive feedback].
An applet demonstrating how cancer can spread [positive feedback].
An applet demonstrating how cows graze [negative feedback].

 

For my job:

An applet demonstrating how a thermostat works [negative feedback].
Worksheets for these simulations [DOC]
An applet demonstrating how hunger and eating affect each other [negative feedback].
An applet demonstrating how a product can come to dominate in the marketplace [positive feedback].
An applet demonstrating how global warming can lead to the ice caps melting [positive feedback].
   
An applet demonstrating how a fan can affect a ball fixed to two rubber bands.  
An applet demonstrating how investing in marketing can affect the population of a city.