Blender - Blender is the open source, cross platform suite of tools for 3D creation.
MilkShape 3D - The MilkShape 3D website has been down for almost one week.
SelfCAD - SelfCAD is an online 3D modeling and slicing software.
Metasequoia - Metasequoia is suitable for beginners, and for professional of 3D modeling and for users using other 3DCG professional software or 3D printer.
Clara.io - Free online 3D modeling software: Design, editor, animation, rendering, & lots of free 3D models. Supports Three.JS, Blend, FBX, OBJ, V-Ray, Babylon.JS, STL.
Fragmotion - Fragmotion is a 3d modeling and animation software.