It's the idea of publishing a list & posting it on the wall in the Registry that got me started.  About 20 years ago, there was kind of a push for a central registry of non-paying clients, the list to be tacked   to the wall  in the registry.  An attorney convinced everyone that it was a bad idea - there was something about restraint of trade or libel or something that he said - I cannot remember exactly what it was - that made everybody back away from the idea.  No-one wanted the liability & possibly it was because of the anonymous nature of such a list - anyone would be able to  post any company name on there, without taking responsibility for the post. 

Of course, clients who are out to stiff us are bad guys & I've posted my disputes with a couple of them here - but the difference was that I sign my name to my posts.  Mostly it was just to get their attention & it did.  On one of my posts, the national vendor manager was on the phone with me about 30 minutes after my post & he straightened out the problem. 

I love the blackmail thing - I'm going to try it with the gas company & see if it works.