FilterPro – Discrete Filter Design
Sometimes there is a need to make a Low-pass, High-pass, Band-pass, or Notch filter in discrete components. Filterpro gives the ability to make Bessel, Butterworth, or Chebychev filters with complete ease. This is very handy if you need a tool to configure discrete components with steep pole drop offs.

Download stand-alone here or full-install from the website.