Pathfinder is a project which demonstrates the A* path finding algorithm.
Born as a byproduct of my MythOS project, this is similiar in style to the Java applet that demonstrates the A* path finding algorithm.
It can find paths in a random map, and you can define different types of terrain. (Although at this point, it is done by editing a python source file).
Pathfinder might serve as a tool for learning the A* algorithm.
The code is python, so it should be easy to understand (*grin*), but I make no guarantees Aas to the correctness or clarity of the code.