Blender - Blender is the open source, cross platform suite of tools for 3D creation.
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.
SelfCAD - SelfCAD is an online 3D modeling and slicing software.
SketchUp - 3D for Everyone
Modelur - Save time and make well-informed decisions during early stages of urban design.
open3mod - A free, Open-Source 3D Viewer designed to make it all easier. Massive 3D Format support