Leonardo (Popularity: )
http://www.dis.uniroma1.it/~demetres/Leonardo/ An integrated C programming environment for reversible execution and logic-based software visualization developed at the University of Rome "La Sapienza".
Opsis (Popularity: )
http://opsis.sourceforge.net A Java applet designed to teach binary search tree algorithms. It is unique in the way it combines programming, proof, ...
LYDIAN (Popularity: )
http://www.cs.chalmers.se/~lydian/ Simulation and visualization environment for distributed algorithms that provides students with an experimental environment to test and visualize the behaviour ...