20. A method of determining query similarity, comprising: determining a volume per unit time of an issued first query over a time period; determining a volume per unit time of issued other queries over the time period; comparing the volume per unit time of each of the issued other queries to the volume per unit time of the issued first query, where comparing the volume per unit time of each of the issued other queries to the volume per unit time of the issued first query comprises: smoothing the volume per unit time of each of the issued other queries and the volume per unit time of the issued first query to remove noise; determining a distance measure between the smoothed volume per unit time of the first query and each smoothed volume per unit time of the other queries; comparing each distance measure to a specified threshold; and designating each of the other queries as similar to the first query if a respective distance measure is below the specified threshold; and identifying ones of the issued other queries as similar to the first query based on the comparison.
27. The method of claim 20 , wherein comparing the volume per unit time of each of the issued other queries to the volume per unit time of the issued first query comprises: weighting the comparison to intervals of the time period of highest variability.