Hello, floorplans from that link was done in http://away3D.com/features/ , but there are more possibilities: any kind of flash engine (or other 3D engine with specific plugin for browser, if it is not flash...sure, flash technology need also plugin, but it is kind of standard, I think . In this web are 3D accelerated experiments in Webgl, maybe standard in future (no plugin is needed, only chrome browser, in safari there is also possibility turn on support for webgl in preferences). http://www.chromeexperiments.com/webgl
PS: other 3d engine with plugin http://unity3d.com/