People share pictures online to increase their social presence. However, recent studies have shown that most of the content shared in social networks is not looked at by peers. Proper metadata can be generated and used to improve the retrieval of this content. In spite of this, we still lack solutions for collecting valid descriptors of content that can be used effectively in the context of social information navigation. In this paper, we propose a mechanism based on persuasive techniques to support peers in providing metadata for multimedia content that can be used for a person's self-promotion. Through an iterative design and experimentation process, we demonstrate how this methodology can be used effectively to increase one's social presence thus building more enjoyable, rich, and creative content that is shared in the social network. In addition, we highlight implications that inform the design of social games with a purpose.