1. A system for clustering documents, the system comprising: one or more processors; and a memory storing program instructions executable by the one or more processors to implement: a first program component operable to generate a document vector for each of a plurality of documents of a corpus, wherein each document vector comprises a plurality of terms from the corresponding document and a frequency score for each term; a second program component operable to generate a plurality of reference vectors based on the document vectors, wherein each reference vector comprises a plurality of terms from the document vectors and a frequency score for each term, wherein the frequency score for each term in each reference vector comprises a random or pseudo-random value; a comparator operable to compare the document vectors to each of the reference vectors to generate similarity values for each of the document vectors; a sorter operable to sort the document vectors based on the similarity values for the document vectors to form a sorted list; and a cluster generator operable to form clusters of documents based on the similarity values between adjacent document vectors in the sorted list.