1) Pass Thru Width like on the Rotary. This would be very useful when using the slider to control volume.
2) Smoothing function on the sliders. Since the sliders currently don't produce all 128 possible valued and as such have a tendency to jump from one value to another a smoothing function is necessary. When a jump is going to occur if the user has not lifted his finger off the slider you should output all values between the old position and the new one.