1. A computer-implemented method, comprising: generating a plurality of scores for each of a plurality of N-grams with respect to each of a plurality of categories based on occurrence of the plurality of N-grams in a plurality of training documents; setting a threshold for each of the plurality of categories based on pre-classification of a plurality of validation documents, occurrence of the plurality of N-grams in the plurality of validation documents, the plurality of scores, and a predetermined false positive limit; generating a statistical content classification model based on the plurality of scores and the threshold; assigning a plurality of weights for each of the plurality of N-grams, wherein each of the plurality of weights is associated with a distinct one of the plurality of categories; storing the statistical content classification model in a data storage device; and allowing content filters to access the statistical content classification model in the data storage device over a network, wherein the content filters classify contents into one of the plurality of categories using the statistical content classification model.