Following are the links to Free, Basic to Advanced CAD Tutorial Videos, useful for both Beginners & Advanced users:
AutoCAD Tutorials
AutoCAD Tutorials For Beginners
AutoCAD Tutorial - 3D Modeling
AutoCAD 2011 Tutorials
AutoCAD Surface Modelling
Lynn Allen AutoCAD Tips and Tricks Booklet Pdf Download
SolidWorks Tutorials
SolidWorks Basic Tutorials
SolidWorks Advanced Tutorials
CATIA Tutorials
CATIA V5 Basic Tutorial pdf Free Download
Nx Tutorials
Autodesk Inventor Tutorials
Autodesk Revit Tutorials