Source: http://en.wikipedia.org/wiki/Friction#Approximate_coefficients_of_friction

Materials Static friction
Dry and clean Lubricated
Aluminium - Steel 0.61  
Copper - Steel 0.53  
Brass - Steel 0.51  
Cast iron - Copper 1.05  
Cast iron - Zinc 0.85  
Concrete - Rubber 1.0 0.3
Concrete - Wood 0.62  
Copper - Glass 0.68-7  
Glass - Glass 0.94  
Metal - Wood(MIN) 0.2 0.2
Metal - Wood(MAX) 0.6  
Polyethene - Steel 0.2 0.2
Steel - Steel 0.8 0.16
Steel - PTFE (Teflon) 0.04 0.04
PTFE (Teflon) - PTFE (Teflon) 0.04 0.04
Wood - Wood(MIN) 0.25 0.2
Wood - Wood(MAX) 0.5