[filterview] is a GUI object for generating and visualizing biquad coefficients. It allows to you manipulate the filter band, frequency, and gain using your mouse. The magnatude and phase are then graphed in realtime as the parameters changed, and the list of biquad coefficients are output. It is inspired by the [filtergraph~] object in Max/MSP. Thanks to Mike Moser-Booth for doing all of the math behind the scenes.

http://puredata.info/downloads/filterview