An intresting link collection from Anastasia PIstofidou at pinterest: http://www.pinterest.com/narkt/capacitors/

• Touché: Enhancing Touch Interaction on Humans, Screens, Liquids, and Everyday Objects publication
• Touche for Arduino: Advanced touch sensing

Components:

• Arduino
• Usb cable
• Shield
• pin headers
• Resister: 10k, 1MOmh, 3,3k
• Capacitor: 100pf, 10nf
• Diode: 1N4148 diode
• Coil / inductor: 10mH (cypax.dk part no: 07.055.0510)
• Water bottle as sensing object.

Create the circuit: http://www.instructables.com/id/Touche-for-Arduino-Advanced-touch-sensing/2/?lang=de

Download the code: https://github.com/Illutron/AdvancedTouchSensing