We describe a virtual-reality widget library and two medical applications built on the widget library. These two applications, education using surface models and radiological volume visualization, make use of collaborative interaction techniques. These techniques support a high degree of precision with respect to manipulation of data and data parameters. The 3D widgets instantiated in these applications are synchronized between clients in order to facilitate the high degree of interactivity necessary for productive investigation of shared medical models and volume data. We discuss challenges that face the investigator in an immersive 3D environment as opposed to that of a 2D desktop environment. We describe how these differences have led us to criteria for development of the shared 3D Virtual Reality (VR) graphical user interfaces (GUIs) used in the biomedical applications presented. We review our educational validations already conducted for the surface model exploration application and preview our future work toward a single advanced biomedical collaboration environment.