11. A system comprising: one or more processors; and a memory, coupled to the one or more processors, storing executable instructions including: a feature extraction module configured to extract features from labeled text nodes for a seed site associated with a vertical of products or services, individual labeled text nodes being associated with an identified attribute targeted for data extraction within the vertical of products or services; a vertical knowledge learning module configured to learn vertical knowledge that characterizes attribute-specific semantics for the vertical of products or services based at least in part on the features extracted; a new web site adaptation module configured to apply the vertical knowledge to an unseen web site and to associate individual text nodes of the unseen web site with an attribute targeted for data extraction within the vertical of products or services; and a data extraction module configured to extract values from the individual text nodes of the unseen web site.
11. A system comprising: one or more processors; and a memory, coupled to the one or more processors, storing executable instructions including: a feature extraction module configured to extract features from labeled text nodes for a seed site associated with a vertical of products or services, individual labeled text nodes being associated with an identified attribute targeted for data extraction within the vertical of products or services; a vertical knowledge learning module configured to learn vertical knowledge that characterizes attribute-specific semantics for the vertical of products or services based at least in part on the features extracted; a new web site adaptation module configured to apply the vertical knowledge to an unseen web site and to associate individual text nodes of the unseen web site with an attribute targeted for data extraction within the vertical of products or services; and a data extraction module configured to extract values from the individual text nodes of the unseen web site. 15. The system of claim 11 , wherein the new web site adaptation module is further configured to: extract new features from the individual text nodes of the unseen web site; predict page level relevance scores based at least in part on the new features extracted from the unseen web site and the vertical knowledge, the page level relevance scores indicating a probability that an individual text node is associated with a particular attribute targeted for data extraction within the vertical of products or services; employ inter-page aggregation to improve the page level relevance scores and determine candidate attribute solutions for the individual text nodes of the unseen web site; and re-rank the candidate attribute solutions based on layout features extracted from the unseen web site.