HAPTICS AND EXTENSIBLE 3D IN WEB-BASED ENVIRONMENTS FOR E-LEARNING AND SIMULATION Topics: Case-Studies and Applications; e-Learning Standards and Tools; Multimedia and User Interfaces; Software Tools for E-Learning; Web-Based Education; Web-Based Teaching and Learning Technologies In Proceedings of the Fourth International Conference on Web Information Systems and Technologies - Volume 2: WEBIST, 309-315, 2008 , Funchal, Madeira, Portugal