OpenArena is a 3d game creation engine. It is a rendering system that can be used for more than just games but it is targeted at games. The basic use being create some game media textures models maps and config files for physics and rules.
Y.A.P.R.M. is a free-as-in-freedom modeller to graphicaly design 3d scenes and generate POV-Ray-files for them. Appart from the basic POV-Ray objects which can be used in CSG operations it supports spline based objects. Furthermore a vast amount of 3d-files can be imported and used with Y.A.P.R.M.