GridSim allows modeling and simulation of entities in parallel and distributed computing systems such as users, applications, resources, and resource brokers/schedulers for design and evaluation of scheduling algorithms. http://www.gridbus.org/gridsim
GAP (Grid Agents Platform) Toolkit for Modeling and Simulation of Mobile Agents in Grid Environments. GAP is an abstraction over GridSim, a Grid Simulation Toolkit for Resource Modelling and Application Scheduling for Parallel and Distributed Computing.