We've now converted every incandescent light bulb we could (around 40-50 of 'em) to a compact fluorescent (CFL). Since incandescent bulbs are only about 2% efficient and CFLs are around 8%, it seems like a no-brainer. CFLs also last about 8 to 15 times as long as the incandescent cousins. After buying and trying a few different brands (and reading some reviews online) we picked up a whole slew of N:Vision bulbs at our local Home Depot. I've read that lighting accounts for 9% of the energy in a typical home. If CFLs use about 20% what a comparable incandescent uses, I figure I could reduce by energy usage by ~7%. We'll see if reality reflects my math.