Here is my port of the Moog ladder filter written using gen~ (Max 6 only). It uses the ICST implementation, with a few added goodies such as additional filter modes (notch doesn't work so great...) and peak-shaping.
It has built-in saturation and can self-oscillate. Filter cutoff is specified in MIDI pitch rather than frequency.
The help-file provides a demo of a monosynth and has controls for key-following, the filter envelope, cutoff, etc.