Lamp Experimental Data - This web pages has results of
measurement results of the voltage and current draw of normal
light bulbs under different conditions. The current draw is
definately NOT a linear relationship with voltage. The resistance
of the filament varies significantly with the input voltage (due
to thermal effects).
Notes on bulb savers - Stay away from bulb savers, green
plugs, and other similar products claiming huge energy reduction.
Your realized savings for these products will rarely approach the
advertised claims and you risk damage to your appliances with some
of these.