POV-Ray is a 3D rendering program, which can create photo-realistic scenes. It is not a 3D modeller -- there is no visual interface. To create scenes you write a script which describes all the elements of the scene. POV-Ray then generates the scene based on the script. This may sound old-fashioned and limiting, but POV-Ray is a very powerful system, and can produce very impressive results. It also happens to be free, which must count for something!
The idea of scripting a scene might sound complicated, but it is actually quite easy to create a simple scene. I hope to include a simple tuturial here -- check back later.