15. The computer program product of claim 13 , wherein the content item comprises at least one of an e-mail, an instant message, a chat message, a text messages, a SMS message, a paging communication, a blog post, and a news item.
13. A computer program product comprising executable instructions tangibly embodied in a non-transitory computer-readable medium which, when executed by at least one processor, perform a method of selecting a content item, the method comprising: accessing an incoming query from a memory device; creating a first set of tokens from the incoming query; computing a first total as a number of tokens in the first set of tokens; accessing a second set of tokens, corresponding to the content item stored in the content item database; determining a degree of similarity by: determining a minimum of a first count and a second count, the first count being a count of a unique token in the first set of tokens and the second count being a count of the unique token in the second set of tokens; and computing a randomized easy signature by: selecting a set of most frequent tokens from the second set of tokens; computing a second total as a number of tokens in the selected set of most frequent tokens; randomly selecting a sub-set of tokens from the selected set of most frequent tokens; determining a number of common tokens based on a minimum of the first count and a third count, the third count being a count of the unique token in the randomly selected sub-set of tokens; and determining the randomized easy signature as a ratio of the number of common tokens and a sum of the first total and the second total; and identifying the content item as matching the incoming query if the degree of similarity exceeds a predetermined threshold.