There are a ton of free programs as well as professional paid programs. Here is a quick list 3d modeling software. Just Google the name for their sites.:

Free 3D softwares:

Google SketchUp
3DCrafter
3Dtin
Anim8or
Art of Illusion
Blender
BRL-CAD
Creo Elements/Direct
DrawPlus Starter Edition
FreeCAD
GLC Player
LeoCAD
Netfabb Studio Basic
K-3D
OpenSCAD
Tinkercad
Wings 3D

Paid 3D softwares:

3DS Max
Alibre
AC3D
AutoCAD
AutoQ3D
Cheetah3D
Cloud9
FormZ
Maya
Magics
NetFabb
Rhino3D
Solidworks
ZBrush