1. A computer-implemented method, comprising: sending a query to one or more information sources associated with a category comprising one or more terms, wherein said one or more information sources are identified by a ranked list of information sources, and wherein said ranked list is generated by ranking a plurality of information sources based on scores for results returned by said plurality of information sources in response to a ranking query comprising at least one keyword and generated from said category, wherein said ranking comprises: receiving the results from each of the plurality of information sources; and determining the scores for the results by (i) determining a quality measure for each keyword, (ii) determining a quantity measure for each keyword, and (iii) determining a score for each keyword based on the quality measure and the quantity measure; and obtaining results from said one or more information sources.