Ad system has four stakeholders - Advertiser, Ad Platform, Content Publisher, and Content Consumer. I guess we need an advertisement model that not only provide

Ad system has four stakeholders - Advertiser, Ad Platform, Content Publisher, and Content Consumer. I guess we need an advertisement model that not only provide benefits to all four but also engages all four stakeholders to determine the quality, ranking and relevance of ad. Automated Context Matching Algorithms are just a first step in this regard. They match the ad with content but they don't take into account the preferences, beliefs, opinion of visitor and content provider. We must allow content publisher and visitor to have an equal say in which ads get served and which not. Atleast they should be allowed to express whether they found ads relevant or not. How about vote up/down system for ads? Will it help in determining the relevance of ads according to visitor? Will user even care to click on it? Another thing that bothers me is how a particular user can be identified and his behavior/preference can be recorded without invading his privacy? How existing ad platforms handle this?