While a bit slick/sleazy in their approach their work revolves around using social psychology principles (social proof, scarcity etc), conversion tricks, clever copy, giving away freebies in order to build up their email lists. These guys eventually upsell on their premium products for a ridiculous price whilst offering their digital product for a "limited time only" to convert users who've got a good amount of value from their give-away products.
There's hardly any regulation in this industry and the FTC has come down hard on these guys on more than one occasion.
