Techniques are provided which engage users and increase social interaction in group buying. Methods and systems may target users with a first advertisement comprising one or more proposed deals based at least in part on the users' electronic calendar entry information. The advertisements may be served and displayed in the users' electronic calendars. Users' responses to the proposed deal may be tracked. Users may be targeted and served with additional advertisements based at least in part the users' responses to the proposed deal included in the first advertisement and the calendar entry information. Users may forward the advertisements to other individuals to encourage them to participate in the proposed deals in order to receive additional discounts.