The World Wide Web (WWW) is emerging as an appropriate environment for business transactions and user-organization interactions, because it is convenient, fast, and cheap to use. Now more than ever, users rely on the Internet for information and news. With well over 433,193,199 websites (Internet Domain Survey 2007) and billions of individual Web pages, finding high-quality information is increasingly challenging. With such a large collection of semi-structured and structured information sources, Web users often suffer from information overload. Efficient tools are required to manage, retrieve and filter this information effectively. Within large Intranets, these tools are also used to extract or infer new information to support decision-making within the establishment.