How does he do it? He uses automated content generation on computers - he has a Windows program and databases, and Bayesian techniques to actually generate Word documents. His favorite topics are long-tail subjects like "the outlook for bathmat sales in India." The video below demonstrates his system at work:
He's also patented techniques to generate games (such as crossword puzzles in any one of 600 languages), quizzes and videos. An example automated game in the video: "A 3-D shooter, featuring a 'clever tomato' that can teach Spanish speakers English". I kid you not. It took him about 5 minutes to generate that game.
As far as I can tell, Parker is not using his technology to create rank-able spam affiliate sites. Most of my friends might say: "What? Why hasn't he created a spam blog empire as well? He'd make millions!" But maybe he's smart - he's staying under the Google spam radar :)
He does have a dictionary web site with automatically generated "word of the day" 3D animations (again featuring a 'clever' talking tomato). The domain names shows that Parker is not completely up on the latest in domaining or domain trademark law: http://websters-online-dictionary.org.
But he does have affiliate links and an interesting approach to a site map on that site...