GIF Animations of Simple Machines

World of Technology has several great GIF animations demonstrating some fundamental mechanics:

http://mytechnologyworld9.blogspot.com/2010/08/complicated-mechanisms-explained-in.html

Seen at right is the radial engine.  The constant velocity joint is my favorite, but it’s also great to learn how a sewing machine really works!

Some great visualizations of interesting and intricate 3D geometry and engineering.