This fabric touchpad was inspired by the properties of piezoresistive materials to measure both amount of pressure applied through the materials and increase of resistance across distance. It is made by layering piezoresistive material between two conductive layers and using the piezoresistive layer to alternatively measure position and pressure.
Instructable >> http://www.instructables.com/id/EJKTF3WGV490JGK/
Adrian Freed at CNMAT has made a much better version of this touchpad and written a paper about it:
CNMAT publication >> http://cnmat.berkeley.edu/publication/support_vector_machine_learning_gesture_signal_estimation_piezo_r
Front and back
link >> http://youtu.be/gPYyuuL-o7k