Left / Right, and Front / Rear.

My Sony 600 DSP had this. First (as the driver) you delayed the sound coming from the left speakers, so that it sounded further away from your ear. It feels like moving across from front to right across a row of seats at a concert. Next, you adjusted the delay on the rear speakers, which basically made it feel like you were getting closer or further away from the stage.

I think EVERY stereo should have this option. Put that in my Rio Car and I will be ecstatic.