1. A data storage medium for web page classification system, comprising: a web crawler for crawling a corpus of web pages; a feature extractor for extracting at least one of the following features from a web page received from the web crawler: a first uniform resource locator (URL) corresponding to the hosting site of the web page, a second URL contained inside the web page that is indicative of a hyperlink to a blog site, at least one substring that is a part of the first URL, and whether the web page contains an ATOM or RSS feed, the feature extractor further configured for extracting the contents of the web page and generating therefrom a set of observed values, wherein each observed value is associated with a feature in the web page that provides an indication that the web page is a blog page, the set of observed values including a first observed value that is generated based on the number of occurrences in the web page of a non-markup word indicative of a blog; and a machine learning classifier communicatively coupled to the feature extractor for evaluating the extracted features and generating a prediction indicating the probability that the web page is a blog page, the classifier containing an algorithm that is trained to apply i) a heavier classifier weight to the first URL corresponding to the hosting site of the web page than to the second URL contained inside the web page, and ii) a heavier classifier weight to the second URL than the substring that is a part of the first URL.