This very simple plugin generates the module dependencies as source for PlantUML and GraphML. You have to copy and paste the source into a viewer like http://www.yworks.com/en/products_yed_about.htm for GraphML.
General usage instructions
Use this plugin if you want to work with the module dependency graph in an external tool. For simple viewing use the internal way: Since IntelliJ 11 there is already the functionality to view a module dependency graph for a certain module. Just press CTRL-ALT-U (windows) on a module in project view.