1. A method for automatically extracting and structuring data from a semi-structured web site, the method comprising: executing instructions stored in a computer memory by a computer processor for: developing a set of experts; analyzing links and pages on the web site by the set of experts; identifying predetermined types of generic structures by the set of experts; clustering pages and textual segments within the pages based on the identified types of generic structures, the clustering is being represented as a Bayesian belief network and including: adding a layer of nodes to the Bayesian belief network, the added layer of nodes including a node for every pair of samples being analyzed, at least one node in the added layer of nodes being an in-same-cluster node which represents whether or not a respective pair of samples being analyzed is in a same cluster, and the set of experts providing their output probabilistic suggestions represented as virtual-evidence nodes; collecting virtual-evidence from the set of experts; calculating a belief in a corresponding in-same-cluster node by propagating beliefs from all the virtual evidence nodes; and calculating a belief in a root clustering node by propagating beliefs from all corresponding in-same-cluster nodes; identifying, based on the clustering, semi-structured data that can be extracted; and extracting the identified semi-structured data from the web site.