Blender 2.60a
http://www.maxwellrender.com/index.php/home/maxwell_for_sketchup
Integrated, No Watermark, 800 max, works also inside the Free versions of Googkle Sketchup 6,7,8 
Free for non profit-licence
Plugin for Rhinoceros or as Stand alone! 
Triangle Mesh Completer by Aiem
Use MeshLabfor convert file format 
IGeo
Accept in Import Export 3dm , OBJ file formats
Open Source: Documentation and tutorials very well presented! 
Only for for happy fews who love to go inside Processing Language 
Wings3D 1.4.1 - Polyhedra as Cutter Plugin( Polyhedra as Cutter Plugin (Reworked) ... - Wings3D - Official Development Forum )
http://www.wings3d.net
Art Of Illusion to Sculptris… Test

Luminance HDR 2.1.0
Don’t know if it was posted before … but have you seen www.3dtin.com. Nothing to install, it’s in Flash in the Browser! There’s a bunch more Flash apps at www.alternativeapps.tk …
http://usa.autodesk.com/adsk/servlet/pc/item?siteID=123112&id=13571320
Softimage Mod Tools. It’s a bit like its bigger brother Softimage, yet has enough features to make free or smaller games with.
b.t.w. I made a search in this topic, and hopefully the link it’s not a repeat. 
