MultiUser environments such as MultiUser Dimensions (MUDs) and MUDs Object-Oriented (MOOs) are text-based collaborative learning environments that are intended to promote the constructivist approach to learning. More recently, they have been integrated with the World Wide Web (WWW), thus harnessing the graphics and multimedia-rich environments available therein. Learners, no longer restricted to text-based objects, can directly experience, manipulate, and create objects in their rich multimedia form. MUDs and MOOs are augmented with synchronous multimedia collaboration technology that provided simultaneous control and viewing of shared documents and applications. In this paper, we propose that multimedia-enhanced MUDs and MOOs (known as WOOs) are open-ended environments that can be used to support different models of learning, such as instruction, construction, communication, social and situated learning