Similar to some recent high-end CD-player vinyl emulators, a feature you could switch on and off which would essentially eliminate any sound when the record was in backwards motion. This allows for some cool faderless scratching effects, although obviously it's no substitute for a bit of dexterity ;)
This is actually a feature I implemented in a very early version about 5 or 6 years ago. We never put it into scratch live because it seemed a bit cheesy, and we have been careful not to insult skilled DJs with gimmicky scratch features. It's actually quite funny to hear that a high-end CD player has come up with the same feature after all this time.