SketchWorlds, based on RealXtend, is unique - a virtual world with architectural and property based visualisation at the heart of the system.
Of note is the ability to import direct from 3DMax and SketchUp allowing for quick and easy modelling within a virtual environment, something that is almost impossible with any degree of detail in other systems such as Second Life.
The movie below details the in-world editor, note the dynamic lighting:
As regular readers will know we have a bit of thing with HDR, SketchWorlds allows real time HDR rendering:
Take a look at http://sketchworlds.com/ for full details, from a first look it seems promising.
Via Digital Urban