I wasn't sure what else to call it... (but yesterday was reminded that it's amplitude modulation, heh. Update: nope. It's filter modulation because the filter is what's being modulated BY the amplitude)
Got playing around processing audio sources through thor and fell into this one. It takes the audio and uses the incoming waveform to modulate it's own LP filter frequency, so the resultant sound depends entirely on the wave-shape of the instrument/audio it's hooked to, it'll be interesting to see what it does to regular audio, I haven't tried that yet.
It does some strange lo-fi things to drums, and gives a different character when inverted.
Threw in a panner for good measure, along with a cutoff pulse. Pan speed/pulse have adjustable rates on independent lfos, so the cycling can get pretty varied.