In this paper, we present I3D, a system that combines the 3D input and high-performance rendering capabilities of high-end virtual reality systems with the data fetching abilities of network browsers. Using a Spaceball, the user can intuitively navigate inside the three-dimensional data, while selecting 3D objects with the mouse triggers requests for access to remote media documents that can be text, still images, animations or even other 3D models. Time-critical rendering techniques allow the system to display complex 3D scenes at high and constant frame rates, making it possible to use it in the context of large scale projects. The system is currently being used at CERN as a visualization and data management tool for the design of the new Large Hadron Collider, and will be used at CRS4 in the networked educational system IPERLER.