Social navigation tools were developed with an aim to guide user exploration of an information space and to inform users' decision making processes (Dieberger, Dourish, Hook, Resnick, & Wexelblat, 2000). In the online bookstore setting, social navigation tools such as book recommendations, user tags and customer reviews address information needs not expressible with keyword search so as to facilitate exploratory activities, which may enhance subjective search experience. In order to examine whether online social navigation tools influence the affective aspects of user experience, theory of flow is applied in this study to form a new evaluation methodology. Impacts of social navigation tools on behavioral variance are also discussed.