DeleD CE - DeleD is a 3D modeler and level-editor combined into one.
3DTin - 3DTin is a browser based 3D modelling tool.
Pmx Editor - PMX Editor is for editing 3D model data to be used in MikuMiku Dance.
OpenFX - OpenFX is an Open-Source 3D modeling, animation and rendering suite.
Anim8or - Anim8or is a 3D modeling and animation program that is aimed at beginners with its intuitive and easy-to-use set of tools.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.