Here are some gems for you 3D artists out there.
Blender- An open-source 3D modeling, animation, and rendering package. Has add-on capability and powerful flexibility. (If you ask me, I am not fond of Autodesk Maya)
Sculptris - A free sculpting program. It can import and export .obj models.
MeshLab - Useful for reducing poly counts of things like rocks or organic things. Has other features I am not aware of.
xNormal - I usually use this for making ambient occlusion maps.
AwesomeBump - Generates normal maps, bump maps, light maps, and other maps. You can load a 3D model and see a real time preview of your texture maps applied to the model.