Blender - Blender is the open source, cross platform suite of tools for 3D creation.
SketchUp - 3D for Everyone
3D Cityplanner - Urban and real estate development at your fingertips. With the 3D Cityplanner it’s possible to create, visualize, analyze and share 3d plans online.
Autodesk Revit - Autodesk Revit is building information modeling software for architects, structural engineers, MEP engineers, designers, and contractors.
Silo - Silo is a focused 3D modeling application with the ability to effortlessly switch between organically sculpting high-poly models and precisely controlling hard-edged surfaces.
MakeHuman - MakeHuman is a free, open source, interactive modeling tool for creating custom 3D human characters.