1. A system comprising: at least one processor for executing: a receiving module to receive, over a network at a social shopping platform, a request from a user in a first community of users, the social shopping platform includes a plurality of network-based marketplaces respectively associated with a plurality of communities, the plurality of communities includes the first community of users that is associated with a first network-based marketplace; a processing application to identify the first network-based marketplace from the plurality of network-based marketplaces based on the request, the request for an activity associated with the first network-based marketplace that is used by the first community of users to transact items of a single domain that is of interest to the first community of users; and a reputation module to update a reputation score based on a user reputation score for the user and based upon the activity associated with the first network-based marketplace, the reputation module further to update the user reputation score based on the reputation score.