Providing an online computer service for creating and managing affinity groups; enabling users of an online virtual community to control read and/or write access to their personal profile information and preferences by other users, who are identified as being in the first user's affinity group; enabling users to find and engage with other users with similar interests based on their participation in online activities; providing for users of an affinity group to share interests, participate in discussions, offer recommendations and reviews of products and services; customizing information and advertising about products, events and services for consumption by the users in each affinity group; enabling users to purchase, borrow or trade products