This assembly of spherical rhombus linkages expands to enclose a volume.  It was designed by Jerome Choe to explore the construction of complex articulated systems. (UCI Robotics and Automation Lab)

Chris Sangwin has a nice collection of linkage movies on his web-site http://www.howround.com.  Particularly nice are the straight line mechanisms found at the link:

http://web.mat.bham.ac.uk/C.J.Sangwin/howroundcom/straightline/exact.html

His example of the Sarrus linkage is also found on YouTube:

Fred Klingener has generated a number of interesting mechanism animations.  My favorite is the Peaucellier straight line mechanism.  You will find a table of 16 or so animations at his site:

http://www.brockeng.com/mechanism/index.htm

Brock Institute Logo

This link connects to a web-page with a number of linkage animations. There are several planar four-bar linkages, several spherical four-bar linkages, and an example of a spatial four-bar linkage called a Bennett linkage that is shown below. This page also includes a number of spherical linkage animations generated by students some years ago. (UCI Robotics and Automation Lab)

http://synthetica.eng.uci.edu/~mccarthy/Linkages.html

This animation was generated by HaiJun Su using POV-Ray. It is a Bennett linkage designed to guide the coupler linkage through three specified task positions: