Virtual museum of curved spaces in 3D 
This video is from the "Virtual Museum of Geomtery" opening event, where the new Collaborative Curved Space Explorer version was showed. One could find more about Krestianstvo SDK and Collaborative Curved Space http://nsuslovi.blogspot.com/2009/12/collaborative-curved-space-explorer-v10.html
It is pure Open Source project, so that everybody could try it by themselves, after downloading the SDK. This video shows, how Collaborative Curved Space Explorer works with Flat, Hyperbolic and Spherical spaces in multi-user mode being installed on the one shared replicated virtual world (island).