Abstract: In various embodiments, direct or indirect specification of an advertisement to be displayed on a web page or other medium being published or administered by a user is received by a computing device. In response, the computing device provides or enables provision of the advertisement to be delivered and displayed to another user that is a friend of the user, and/or another advertisement to be displayed subsequently to the user. In various embodiments, the computing device provides or enables provision of an advertisement to be displayed for the user based on the intersection of the preferences of the user with the preferences of a publisher or administrator of content being consumed by the user. In various embodiments, the computing device tracks propagation of an advertisement through a social network of users, and/or determining the nature and amount of influence a user has in propagating an advertisement through the social network.