31. A computer-implemented system comprising: a search engine configured to use a usefulness prediction generated from a given universal resource locator (URL) as a part of an operation performed by the search engine involving the given URL; a usefulness predictor that generates the usefulness prediction from the given URL using a usefulness model by: determining a quantity of negative URLs and positive URLs identified by a training set; obtaining a positive usefulness prediction probability value in connection with the given URL using a count of one or more features extracted from the given URL and the usefulness prediction model; obtaining a negative usefulness prediction probability value in connection with the given URL using a count of one or more features extracted from the given URL and the usefulness prediction model; and comparing the positive usefulness prediction probability value with the negative usefulness prediction probability value to generate the usefulness prediction in connection with the given URL.
33. The system of claim 31 , said search engine further comprising a search component and the given URL is a part of a set of search results generated by the search component, the search component configured to: request the usefulness prediction in connection with the given URL; determine whether or not to remove the given URL from the set of search results using the usefulness prediction requested in connection with the given URL.