Adsense testing new feature
Google adsense are testing a new feature called Advertise on this site which places a link in Adsense spots that allows advertisers to advertise on that particular site.
Google Adsense are testing a new Adsense feature called ‘Advertise on this site’ which you can see in action on some pages at ask the builder. I’ve included this screen capture and have highlighted the link that sends advertisers to this page where they are told about the site and then invited to sign up as an advertiser for it through Adwords. You should be able to see it on the top/middle adsense on this site