Black Hat PPC is an application of the black hat approach - read the rules, test the rules, bend and test the rules then stick with what works - to Pay Per Click marketing.
My first readings on the topic are for a man who, inter alia, is familiar with how the top dogs rank for Poker queries. That is, he is the absolute elite when it comes to ranking for competitive search terms, largely because he's got an in-depth knowledge and understanding of blackhat SEO. I'm referring to Mr. Mikkel deMib Svendsen.
Mikkel wrote The Art of Black Hat PPC Management. I think it was one of the most influential things I've ever read and perhaps one of the best written as well. What's particularly interesting is his point about blackhat PPC being virtually risk free. SEs won't ban an infringing advertiser; at most they'll temporarily remove his ads. The reason is that they want the advertiser's money.
In a more recent bit of reading (Mikkel's article was written for the now defunct E Marketing News, back in 2005), the unnamed author of this PPC blog has written a sort of update/refresher (without saying so explicitly) on blackhat PPC. Some of the ideas are original, some are the same Mikkel was advocating 2 years ago. In particular, his article is geared towards affiliates looking to flaunt network and merchant rules on PPC bidding. His inspiration comes from the SEWatch, apparently.