Behaviourspace is a feature, or component of the NetLogo software for Agent-Based Modeling. Netlogo's main graphical user interface (GUI) lets you define widgets such as buttons, sliders, choosers, etc. A Behaviourspace is another GUI that "calls the main GUI", to run many instances of the model with systematically permuted input-parameters. You can also specify output files for saving the results of the model-runs.
Netlogo's Behaviourspace GUI is similar in functionality to Weka's "Experimenter" GUI.