Data warehousing is an emerging technology that greatly extends the capabilities of relational databases specifically in the analysis of very large sets of time-oriented data. The emergence of data warehousing has been somewhat eclipsed by the simultaneous emergence of Web technologies. However, Web technologies and data warehousing have some natural synergies that are just now being recognized. First, Web technologies make data warehouse data more easily available to a much wider variety of users both internally and externally. Since the value of data is directly related to its availability for exploitation, Internets and intranets help increase the value of the data in the warehouse. Second, data warehouse technologies can be used to analyze traffic to a Web site in a wide variety of ways in order to make the Web site more effective. This chapter will focus on the latter of these synergies and show, through an evolving example, how a simple data set from the Web log can be enhanced, in a step-wise fashion, into a full-fledged market research data warehouse.