13. A method of personalizing a search of a document collection to a user, the method comprising: monitoring a plurality of documents accessed by a user; identifying a plurality of first phrases present in one or more of the accessed documents; for each of the identified first phrases, identifying one or more corresponding first related phrases, wherein the one or more first related phrases are related to the corresponding identified first phrase; storing a user model associated with the user, and comprising a plurality of cluster counts, each cluster count associated with a predetermined cluster that includes a plurality of first related phrases, and storing a count of a number of instances of first related phrases of the cluster appearing in a document accessed by the user; receiving a query from the user, the query including one or more second phrases; selecting search results comprising a plurality of documents responsive to the query; identifying, by operation of a processor configured to manipulate data within a computer system, one or more second related phrases that are related to the second phrase(s) of the query and that are present in the user model; weighting a plurality of scores of a corresponding plurality of the search results according to the cluster counts of the identified one or more second related phrases; ranking the plurality of the search results for presentation to the user according to their weighted scores, to provide personalized search results; and presenting the personalized search results to the user.
13. A method of personalizing a search of a document collection to a user, the method comprising: monitoring a plurality of documents accessed by a user; identifying a plurality of first phrases present in one or more of the accessed documents; for each of the identified first phrases, identifying one or more corresponding first related phrases, wherein the one or more first related phrases are related to the corresponding identified first phrase; storing a user model associated with the user, and comprising a plurality of cluster counts, each cluster count associated with a predetermined cluster that includes a plurality of first related phrases, and storing a count of a number of instances of first related phrases of the cluster appearing in a document accessed by the user; receiving a query from the user, the query including one or more second phrases; selecting search results comprising a plurality of documents responsive to the query; identifying, by operation of a processor configured to manipulate data within a computer system, one or more second related phrases that are related to the second phrase(s) of the query and that are present in the user model; weighting a plurality of scores of a corresponding plurality of the search results according to the cluster counts of the identified one or more second related phrases; ranking the plurality of the search results for presentation to the user according to their weighted scores, to provide personalized search results; and presenting the personalized search results to the user. 19. The method of claim 13 , wherein selecting search results comprising a plurality of documents responsive to the query comprises: identifying an incomplete phrase in the query; replacing the incomplete phrase with a phrase extension, wherein the phrase extension of the incomplete phrase is a super-sequence of the incomplete phrase that begins with the incomplete phrase, and wherein the incomplete phrase predicts the phrase extension; and selecting documents from the document collection containing the phrase extension.