I’ve heard about the electronic gizmos that don’t work, the cathodic protection that is for in water usage, and of course the messy oil sprays, and i remember reading that positive ground causes rust to occur more rapidly, could a constant small load negative ground prevent rust?
Any other rust prevention ideas are greatly appreciated
Can you tell us about your application and what you’re trying to protect?
Move to southern California or Arizona.
its for a car, i wondered if a small continuous load has ever been shown to reduce oxidation of iron, a few eneloops charged once a week would be a simple modification
also you never know what new ideas have been invented but are not yet well known, someone on BLF had mentioned a product called evaporust a while back that my google-fu never uncovered
Move to Arizona…
but with your 500,000 lumen monster pointed at me i can’t sleep at night
The fellas at wikiHow say to keep your car clean and dry. Makes sense.
They recommend the Jig-A-Loo spray to ward off the rust (which also never sleeps).
http://www.jigaloo.com/us/e_products_jigaloo_uses_home.php
There is an interesting video (find link under the picture of the can).
It’s from Canada, eh?
I haven’t tried it, but will buy a can when I see it.
Edit: Don’t spray it on your tire treads! 
Cathodic rust protection like ocean going ships use is cheap to make.
Existing “clean” metal is a must for application site.
A sacrificial anode made of zinc is charged with super-low amperage High PWM dc current.
No longer available at JC Whitney, it was comprised of zinc tabs screwed to rust areas and connected to the module.
I had thought you could take nickles or pennies and burn off the copper coating with Hydrochloric [Muriatic] acid and use as an anode.
A 555 type timer circuit banging out DC high voltages at sub-amp levels should work fine.
Please note several snake-oil salesmen ruined the reputation of this proven technology.
These cheap-o units usually had a 9v battery or/or no high frequency output circuits.
Here’s a link to a system, don’t have any idea if this one is valid technology or not.
http://www.rustguardian.co.uk/parts-of-cat.html
Another vendors unit, patented in several countries.
http://www.couplertec.com/index.php?option=com_content&view=article&id=119&Itemid=200007