Piggyback the Kill-A-Watt's opamp and feed them to the Arduino's ADCs, which are then read out and fired over serial to a python script for plotting
Here is a quick writeup: serialKAW: Serial readout of Kill-A-Watt
Example Graph:
Final KAW & Arduino assembly on lexan:
ADC piggybacks soldered to the KAW's opamp:
*please excuse the shotty looking soldering, i promise it works =P
