Successful commerce relies heavily upon the reputations that the different parties acquire through their dealings with each other. We view an e-commerce community as a social network, which supports reputations both for expertise (providing good service) and helpfulness (providing good referrals). We study the small-world phenomena such as the emergence of sub-communities, and pivot vertices (which link different sub-communities) in the social network, and discovered that the quality of the network improves with the presence of a pivot.