A method and system for measuring an Internet user's level of interest in one or more subjects. For a given subject, web pages that are sent to the user are analyzed to determine how many keywords related to the given subject appear in the web pages. The keyword count is then used as a basis to establish a measure of the user's interest level in the given subject. The analysis may take various forms and can be carried out over successive time periods, so as to regularly update a measure of the user's interest level in the subject. Provided with a measure of the user's interest level in a given subject, a service provider can then tailor services for the user accordingly.