I read Orrin's bit about using graphite electrodes for electrolytic derusting. I saw some cheap on ebay and picked up some, maybe $10. The first ones arrived smashed up, the second ones showed up intact. They're about 8" long, maybe1/2x1" rectangular bar (very roughly). They look fragile. As I said, they were over $5 apiece. They will probably work fine, although I often need an electrode that is longer than that.
Today I was rooting around industrial South Seattle looking for a used but usable welding ground clamp and I noticed these long perfectly round things that looked just like graphite. I picked one up -- it's 12" long, 3/8" diameter, looks pretty strong, looks real conductive. It's a scarfing electrode, first unclad one I've seen, and it must be made of some sintered carbon. They had hundreds and hundreds available for 35¢ each. Skeptical, I bought one. I just hauled out my DVM and my pointy-sharp leads and probed in in ohmmeter mode. End to end it's 2 ohms or less (my meter isn't accurate in that range) and it appears to be just as conductive on the sides as on the ends. In short, it appears to be a real good candidate for use as an electrolytic derusting electrode!
I'll test it and report. This would be great if it works like I hope it does, it would mean electrodes that don't rust, no cruddy solution, without the huge expense and fragility of graphite.