Just a parallel insert with variable +/- 100 sample delay. I haven't seen something quite like this, so I made it.
1. load effect
2. hit phase button.
3. adjust sample and mix til you hear the "pumping"-effect. Many times you will not need to adjust sample offset at all.
4. hit phase button and adjust mix to taste.
Now, if I only could get it to do this automatically automatically

UPDATE 28.01.09:
- Better sample offset handling. Dry signal is not delayed at '0' and below.
TODO:
Fix XTC-mode
Mono version.