There is a support and discussion forum for Vensim and other topics in system dynamics. You can access this using the Help menu from Vensim (Help>Online Form. The direct link for this it http://www.ventanasystems.co.uk/forum and you can also reach it through http://www.vensim.com/forum.
World Wide Web
The World Wide Web contains many sites of interest to system dynamics and other simulation modeling. The sites listed here all contain links to other sites.
The Vensim Home Page (http://www.vensim.com) contains information about Vensim and has a number of downloadable programs including Vensim PLE.
Discussion Forums and Mailing Lists
system-dynamics
The system-dynamics forum provides access to announcements and discussion related to System Dynamics. To access it go to
http://www.systemdynamics.org/forum
There is also a wiki at
http://www.systemdynamics.org/wiki
To post to either you will need to register at http://www.systemdynamics.org/cgi-bin/sdsweb
K-12
The K-12 mailing list for the use of system dynamics in primary and secondary education. For more information visit http://www.clexchange.org/bb/k12_discussion.htm
Distance Eduction
For a more complete academic grounding in system dynamics there is an excellent distance system dynamics program offered by the Worcester Polytechnic Institute (WPI). This is a distance program in system dynamics that includes both introductory courses, applications courses and a number of advanced topic courses. There are both certificate and degree options. See http://www.wpi.edu/Academics/Depts/SSPS/Graduate/index.html for more information.