Bolt Classic
Freeware
Bolt Classic
Bolt Classic allows you to easily make bolt animations and in particular Jacob's Ladder style animations. The green lightning animation in the pipes to the left were made using Bolt, and it took very little time at all. The animated gif below shows how the bolt dialog gives you instant visual feedback as you tweak the various bolt settings.
To start bolt, select two object from which the bolt will ride between. After you select Bolt from the plugin menu, you get the above dialog. Enter the start and stop objects in the first two boxes. The bolt animation starts and you can adjust the various values with feedback. The start and stop time determines when the animation will begin and end. Many bolt animations can use only a few frames looped for convincing results, so don't overdue the length. The animation to the left is only 12 frames long.
Bolt Path
The two controls under Bolt Path determine the Complexity of the bolt. Complexity determines how many breaking angles (points) there will be, and Spline type determines how the breaks are interpreted. Linear will give you the quickest render results. The other options will softly interpret the spline points and significantly increase the resulting SweepsNURBS' complexity. It's there if you need it.
Bolt Cross Section
Bolt uses a uniform circle spline as the cross section for Bolt. Arc Width determines the radius of the circle cross section. Subdivisions determines the uniform subdivisions of the spline cross section. The higher the number you use, the more complex the cross section becomes, and the longer it will take to render. For most animations the lowest setting (1) is the most desirable.
Behavior
Movement determines the size of the movement with higher numbers resulting in bigger, more chaotic bolts. Constraint constrains the width of the bolt so you can put some space between the bolt and the axes of the poles (end objects). Start and End Tapers enable you to constrain the movement of the bolt near the poles. The allows you to make bolts that move more violently in the center than at the ends. Random seed lets you change the seed of the object so if you have identical bolts they will behave differently given different seed numbers.
For those interested in learning more about Jacob's Ladders, the following website has info about Jacob's ladders as well as instructions on how to make your own real world version. Please be careful as the real thing can be deadly dangerous.

http://www.misty.com/people/don/jacobs.htm