What they wanted was to send the search query that the user had typed into Google to us, and have our advertising partners provide an Ad, and they would inject it ahead of Google's ads.
For which they would share the revenue that the Ad partner was paid 50/50 with us. And for this service they said our cut would be $10K - $20K per week.
The funny part was they required to be notified immediately if Google changed its page layout because, well they needed to blend in or the game was up. I wrote a grease monkey script to change the page background after ads had loaded on a Google search engine results page (SERP) and yup, you could see their ad sitting there.
Of course Google would catch on, especially when people complain that Google was showing them ads for inappropriate products or what not and Google would investigate and track down the front doing the injecting. The half life of these fronts seemed to be 6 months to a year depending on how greedy they got. The people behind the front would vanish and pop up under a new name somewhere else.
The sad thing, for me, is that when you put your infosec hat on you realize its super easy to phish an unsuspecting someone by sending fake mail from a friend for a cool backdrop or display toy. Once they are on the hook you can wait until they search for something on Google and inject a very nice result for them to click on that stops off at your drive by zero day site to pick up your payload and its off to the races.
[1] From the article -- "... then proceeded to quietly inject ads inside Google and Bing search results."