Abstract: For the advances of Internet technologies in recent years, Electronic Commerce (EC) has gained many attentions as a major theme for enterprises to keep their competitiveness. Among all possible endeavors for the EC, research has shown that effective management of customer relationships is a major source for keeping competitive differentiation. Therefore, it is common for an enterprise to promote its customer relationships by prospective information systems to achieve the so-called Customer-Oriented EC. In this study, many systems have already been presented in recent years: (1) Customer Decision Support (CDS), (2) Customer Relationship Management (CRM), (3) Customer Knowledge Management (CKM), (4) Recommendation System and (5) Intelligent Agent. In general, these systems emphasize on benefiting enterprises by means of customer information; customers in contrast receive less benefit through sufficient information from enterprises. To address this issue, Consumer Support Systems (CSS) is then proposed that supports effective information provision from enterprises to customers where sophisticated management mechanisms are employed to help on their decision making. For their usefulness on enhancing customer relationships, we review in this study, these existing systems by presenting their characteristics and discussing how these characteristics are useful for enhancing customer relationships. Amongst them, in particular, for CKM and CSS that are most recently concerned, we review also their architectures that address on their characteristics to provide guidance on their constructions.