John Battelle points to a paper on Pay Per Click search. It’s a quick read (6 pages) offering an overview of the Pay-Per-Click (PPC) search engine market and ideas on how to optimize campaigns for maximum results.

You can download the PDF here.

And… if you want to learn more about Pay Per Click advertising (Google Adwords in particular), be sure to check out Andrew Goodman’s book, Winning Results with Google AdWords.