Users who visit a network site typically visit other sites in the same session. The surfing pattern or “trail” through the pages may be significant once aggregated, because it outlines the underlining relationship between those pages or sites. Once such user navigational trail data is available, the relationship between network sites on such user trails may used to make various decisions regarding advertising and keyword management. Additionally, the relative popularity of each trail may be used to rank or compute relative weights for the various user trails. Such information may then aid in keyword suggestion and advertising decisions.