MOUNTAIN VIEW, California: Forever restless for outside-the-box thinking and innovative business models, Google is reportedly mulling charging for ads on a cost-per-action (as opposed to a cost-per-click-thru) model.

This would likely see advertisers paying for search ads on a cost-per-sale, or cost-per-free-trial basis. Such a system, which would virtually eliminate so-called click fraud, is currently in pilot in an unidentified region of the US.

Pay-per-action ads will not appear on the main search page but only on Google's network.

Sergey and Brin's driven dudes also announced a new format for advertisement links embedded in the 'editorial' text of a page that would ape the characteristics of that page.

Some observers are dubious at such a move, suggesting it could become an "ethical grey zone" for Google if the web titan is seen to be creating incentives for website owners to endorse or promote advertisers in the context of 'editorial' articles.

Data sourced from; additional content by WARC staff