Here is a great site with resources on various types of mechanisms. There are many great animations, some of which are interactive so you can plug your own numbers into the system and see the results.
Mechanisms 101 has animations and information about: linkages, indexing mechanisms, gears, pumps, couplings, pneumatic systems, electronics, and many miscellaneous mechanical things. You will need the Flash player plug-in for your browser to see most of these great resources.
Here the link to Mechanisms 101.
[ Thanks Steve! ]