Approaches to measuring power consumption

I'm trying to build an arduino based power meter for a home.

Based on the research I've done, (mostly googling ;) ) I've seen that many designs use inductive current sensors. These are basically loops of wire that are placed around the wire carrying the current.

I would like to know if there are any other approaches to measuring current and which one is the best. Having a low cost is a priority.

I have seen some people hack into those kill-a-watt devices

How accurate do you want the power measurements to be. Inductive pickup clamp type devices arnt very accurate as they dont know anything about phase angle, so cant tell the differance between watts and VA, and they only work with sinusoidal current waveforms, so will be inaccurate with loads with switchmode power supplies. The only accurate way to measure power consumption, is to both measure the voltage and current and compute the RMS value of both to obtain the power. There are dedicated ICs available that do all you need, like this.