While many people complain about the lack of integrated rendering inside SketchUp, there is no lack of options... From free till expensive, from simple to advanced (not necessarily in that order).
So which rendering engines are available for SketchUp? Let's see... I think I have talked about it already.
http://cad-3d.blogspot.com/2010/12/renderin-radiosity-rendering-for.html > about Render[in]
http://cad-3d.blogspot.com/2008/06/rendering-for-sketchup.html > about Podium, IDX, Vue, Piranesi, Atlantis, VRay, Maxwell, FryRender, Indigo, Kerkythea, POV-Ray, LuxRender, Sunflow, iClone
http://cad-3d.blogspot.com/2008/06/accurender-nxt.html > about Accurender nXt
http://cad-3d.blogspot.com/2008/06/free-but-last-nvidia-gelato-gpu.html > about nVidia Gelato (retired)
http://cad-3d.blogspot.com/2007/04/free-indigo-renderer.html > about Indigo
I will quit now, as this is getting to much back in time... and I haven't even mentioned the regular rendering software, such as 3ds Max, Lightwave, Maya, Cinema4D...