1. A method of refining a received query, comprising: processing said received query so as to generate an initial group of ranked documents corresponding to the received query, wherein each document in all or a portion of the documents in said initial group of ranked documents is associated with a respective set of precomputed ranked candidate terms such that each candidate term in said respective set of ranked candidate terms is embedded within said document; selecting, in accordance with a selection function, a subset of candidate terms that are in one or more of said respective sets of ranked candidate terms; and presenting, in response to the received query, the initial group of ranked documents and said subset of candidate terms.