I have used an arduino mini for ADC of a 4 wire resistive touchpad, along with a momentary push to make button and blinkm LED, to send midi CC to a korg kaoss pad.
The push button is used to actuate the hold feature of the kaoss pad, while the pad controls the pad (intuitively).
The blinkm cycles through random hues under the pre-stored script "mood light". When the pad is touched the blinkm changes hue in response to values from the pad.
I haven't used a separate touchpad controller (so no ps2 library needed!). This will be eventually mounted in a guitar much like the Manson Guitars made for Matt Bellamy (Muse)
See this video for a quick demo.