Random Walk 360
Turtles take a random walk upon a plane. As opposed to a more-standard random walk, where the 'walker' is restricted to only moving along a square lattice, here a turtle can turn in any of the 360 degrees around a circle.
For detailed instructions on using the program, take a look at the info window from the Random Walk 360 model.
Click on one of the pictures to see a quicktime movie of the model: