Pathfinding-genetic is a project mainly written in JavaScript, it's free.
Pathfinding using a Genetic Algorithm
This is a genetic algorithm which finds a path between two points while avoiding obstacles.
Magic. Well, actually JavaScript + canvas.
It's for COMP6037 Evolution of Complexity, at the University of Southampton - plus it's fun.
Have a look at http://www.tomokas.com, or http://www.twitter.com/tomokas