100 definitions of Simulation:
http://www.scs.org/magazines/2011-04/index_file/Files/Oren%282%29.pdf
Introduction to Simulation (Excel example)
http://people.brunel.ac.uk/~mastjjb/jeb/or/sim.html
Various links about Discrete-Event Simulations:
http://www.courses.vcu.edu/MATH-jrm/OPER641/slides641.htm