This paper describes how RelevantKnowledge applies the best practices of traditional media research to the world of World Wide Web measurement. RelevantKnowledge provides the World Wide Web marketplace with audience demographics site visit statistics and additional usage-related information from a random sample of recruited participants. Each panelist's computer whether at home or at work is outfitted with proprietary monitoring software which provides a continuous data stream to the RelevantKnowledge processing system. The panel methodology has been built using the highest quality features of traditional media measurement updated and fitted to the Web environment. The paper touches on a number of significant challenges presented by this approach along with solutions.