15. A computer-implemented method, comprising: defining a category comprising one or more terms; generating a query based on said category, wherein said generation step is performed in response to said defining step; sending said query to a plurality of information sources, wherein each information source comprises a plurality of information entities; obtaining results from said plurality of information sources; and ranking said plurality of information sources based on scores for results returned by said plurality of information sources in response to said query to obtain a ranked list of information sources associated with said category; wherein the query comprises at least one keyword and wherein the step of determining the scores further comprises the steps of: determining a quality measure for each keyword; determining a quantity measure for each keyword; and determining a score for each keyword based on the quality measure and the quantity measure.
15. A computer-implemented method, comprising: defining a category comprising one or more terms; generating a query based on said category, wherein said generation step is performed in response to said defining step; sending said query to a plurality of information sources, wherein each information source comprises a plurality of information entities; obtaining results from said plurality of information sources; and ranking said plurality of information sources based on scores for results returned by said plurality of information sources in response to said query to obtain a ranked list of information sources associated with said category; wherein the query comprises at least one keyword and wherein the step of determining the scores further comprises the steps of: determining a quality measure for each keyword; determining a quantity measure for each keyword; and determining a score for each keyword based on the quality measure and the quantity measure. 16. The method of claim 15 , wherein the step of determining a quality measure further comprises the steps of: determining how many times each keyword appears in each document accessible through the results from one of the information sources; determining how many documents are accessible through the results from one of the information sources; and dividing the number of times each keyword appears by the number of documents to determine the quality measure.