1. A method implemented on a computing device having a processor for recommending searchable web sites to a user, comprising: using the computing device having the processor to perform the following: obtaining query behavior using client-side query behavior logs; discovering searchable web sites using the client-side query behavior logs; inputting a search query from the user; submitting the search query to a general search engine to obtain a query language model; computing a probability of each searchable web site given the search query by using the query language model; ranking each searchable web site based on the computed probability; creating a list of top-ranked searchable web sites based on rank to obtain a ranked list of recommended searchable web sites; and displaying the ranked list of recommended searchable web sites to the user.