SketchUp is an intuitive, fun and free for anyone to use 3D sketching program for the conceptual phases of design.
The application lets you model anything you can imagine, - redecorate your living room, invent a new piece of furniture, model your city for Google Earth, etc.
You can build models from scratch, or you can download what you need.
I'm looking for V-Ray for SketchUp.
A nice freeware tool, which provides good number of features for a free application, especially taking into account that it is free to use.
It is one of the easiest 3D modeling apps I came across. It deserves some attention, if just for the reason of being free.