This applet explores a shape generation system which used to be commonly explored in Logo: Stepping forward a certain amount, rotating by a certain angle, and then repeating. To generate a "1, 2" 90 degree shape, for example, you would move
* Forward 1 step
* Rotate 90 degrees
* Forward 2 steps
* Rotate 90 degrees
* Then repeat the above steps until bored (or until you return to your start point).
If only one number is used for the step, you generate a square. With two numbers, you generate a rectangle. With three or more numbers, however, more interesting shapes appear.
You can change the list of lengths being used, and the angle to turn through after each forward step.
EDIT: I've updated the sketch so that you can now control the number of 'steps' in the spiral from 0 up to 72.