A system dynamics application is the combination of a model and a user interface. A key to building effective applications necessitates spending some time on model layout and the software engineering techniques that ultimately improve model quality and lend models to application development. These include module coupling and cohesion, naming conventions, modeling team interaction, and standards. The ultimate success of an application is measured by use. There are traditional and novel creative ways to make useful applications using the available interface tools. Extending a model and interface beyond the usual system dynamics constructs may lead to more effective applications.