AutoDesk
A variety of CAD software, including AutoCAD, Revit, 3DS Max, Inventor, etc. available for free to educators and students
https://www.autodesk.com/education/free-software/featured
Blender
“Blender is the free and open source 3D creation suite. It supports the entirety of the 3D pipeline—modeling, rigging, animation, simulation, rendering, compositing and motion tracking, even video editing and game creation.”
Free CAD
An open sources parametric modeling CAD program
Home By Me
A free web 2.0 architectural design CAD program
Libre CAD
A free, open-source CAD program
Resistor Color Code Challenge
An online game for learning to read the values of resistors
http://nreeder.com/Flash/colorCode.htm
Ruler Game
A web 2.0 app that reinforcing reading a ruler
Sculptris
A digital sculpting and 3D design software; free download available
http://pixologic.com/sculptris/
Sketchup
A 3D modeling program; limited version is free to students and educators
TinkerCAD
A relatively simple 3D CAD program
Wings 3D
A free, open source 3D modeling program