AnyLogic - AnyLogic has changed simulation modeling and expanded its application into complex business environments. The unmatched flexibility of multimethod modeling allows users to capture the complexity of virtually any system, at any level of detail.
Cisco Packet Tracer - Download Cisco Packet Tracer, an innovative network simulation and visualization tool used by Cisco Networking Academy students and instructors.
FlexSim - Simulation software to model, simulate, predict, and visualize systems in manufacturing, material handling, healthcare, warehousing, mining, etc.
GNS3 - GNS3 is a graphical network simulator that allows simulation of complex networks.
Simio - Facility design simulation & production scheduling
Paessler Multi Server Simulator - Paessler Multi Server Simulator is inexpensive and robust software that helps you power massive-scale testing.