The evolution and commercialization of Web Information Systems (WIS) since 1991 has gradually shifted the focus from basic design issues to feedback analysis, visualization techniques, and agent-based negotiation support. Even during the early stages, WIS design efforts turned out to be quite substantial in scale and required a planned, managed, and structured approach. Adaptive solutions avoid redundant repetition, facilitate navigation, and increase the perceived value of provided information or services. Digital agents as proactive, goal-oriented systems promise to increase flexibility and will radically change inherent characteristics of electronic commerce. An evolution-based framework for WIS is provided and software agents are classified according to their functionality and architectural attributes into information agents, co-operation agents, and transaction agents. In this last stage of the framework, agents independently search virtual spaces and identify suitable business p...