+ + + Free & Open Source Global Illumination Renderer +

[Smoother]

http://toxicengine.sourceforge.net/index.php

toxic is an open source project, available on SourceForge, and licensed under the GPL license. That means that:

toxic is free for commercial and non-commercial use. 
toxic sources are freely available, modifiable and redistributable. 
toxic sources may be used in any open source project licensed under the GPL license.

Looks very good!
I'll try it!