Like the citation network of scientific publications, the Web is also a graph where pages are connected together by hypertext links or “sitations”. In the new research field Webometrics, scholars have investigated equivalencies between citationist concepts established in bibliometrics and hyperlinks networks. This paper focuses on the possible analogy between co-citation and co-sitation to structure Web universes. It reports an experiment in the field of bibliometrics and scientific indicators. Several technical aspects that must be dealt with are reviewed. Co-sitation seems a promising way to delineate topics on the Web. However, the analogy with traditional co-citation is deeply misleading: many precautions must be taken in the interpretation of the results.