That is awesome. I've heard about something like that. So here's what he did. The purpose was to reduce cymbal bleed in a snare track without killing the top end of the snare.
1. Duplicate the track.
2. Add compression to the duplicate, then high pass it at about 700Hz.
3. Reverse the phase on the duplicate and blend with the original.
4. Raise or lower the level of the duplicate to control the amount of cymbal reduction.
I will be trying this tomorrow.