Added and fixed some controls.
Distance: The lightning appears if the two locators are at a minimum distance to the entered value. The thunder always appears if the value is to 0.0.
Seed: Animating this value will generate different lightning.
Offset: Another movement direction of points.
Download link for Maya 2013.
Run thunderNodeCmd in script editor (mel).
Windows 7 (.mll):
Let me know if it works!