Touch Lamp Control Parts
See http://hackaday.com/2011/11/21/simple-touch-sensors-with-the-arduino-capsense-library/


  Ever thought of using touch sensors on your projects but didn’t because it would be too much work? [Paul Stoffregen] proves that it can be pretty easy if you use the CapSense library for Arduino. Here he’s created three touch sensors, connecting them to the Teensy microcontroller with two resistors each. The larger resistor (looks like 4.7 megaohms here) sends a signal through the copper pad which is read by the secondary pin. Here that pin is protected from electrostatic discharge with the 1k resistors. The microcontroller takes a reading by measuring how long it takes the voltage to change on the input pin.


Some microcontrollers (of the sort used in Arduinos) have support for touch sensing.