Abstract: Conversations in an online content universe are monitored. A conversation index is generated in social media. An individual conversation is defined by user-selectable input terms. Publishers that influence a conversation are identified. The system generates an influence ranking of site's that influence a particular conversation. The system permits ads to be placed on sites based on the sites influence on the conversation. The system can be updated to permit ads to be targeted based on current influence rankings. The influence ranking is used to perform online advertising targeting and placement. Additional marketing filters, such as demographics, historical performance, and return on investment, may be used to adjust an initial influence ranking based. The ad placement may also be expanded to include related conversations, inlinking sites, and/or outlinking sites.