There is an explosion of 3D software packages. These are but a few of the offerings, and the landscape is constantly changing. An influx of gaming engines with capabilities far exceeding the 2009 levels give us even more choices. As usual, only the free stuff or trials are listed.2
POV-Ray is a popular rendering engine. Models are built in another application, but POV-Ray is used for high-quality output.
DAZ Studio is an application for posing and rendering 3D models, chiefly the realistic human models that DAZ offers. The software is offered as a free download for Mac and PC users. DAZ has been very aggressive about getting users on their platform because they maintain an extensive online marketplace of models and plugins.
Blender is the undisputed king of open-source 3D programs, with a lively, active development community and a feature-rich, stable version for practically any platform.
Pixie is an “open-source Renderman,” essentially the FOSS version of the popular Renderman rendering engine used by many professional studios, like Pixar (who developed Renderman) and Disney. These kinds of renderers are actually a bit difficult if you’re not a computer person. They can take some time to set up, and are often command-line driven.
Aqsis is another Renderman-based rendering engine, with an emphasis on photorealistic lighting and rendering.
Art of Illusion is a Java-based 3D modeler.
LuxRender is a physics-based unbiased render engine. Which is to say images made with it are very realistic, with a photographic quality.