I am still amazed at the number of houses I show and incandescent bulbs are burning brightly. One of the quickest pay backs* is replacing these bulbs with LED bulbs.  I would have said CFL's a year or two ago, but prices have been falling on LED's as dramatically as high def TV's.   A few weeks ago Ace Hardware had a special discount subsidized by FOCUS ON ENERGY rebates on 800 lumen LED light bulbs.   The unbelievable price was 4 bulbs for $1.00.    Lumens are the light output (brightness) of an LED bulb.  800 lumens puts you at the equivalent light output of the "old school" incandescent 60 watt bulb.   The big difference is the LED bulb of 800 lumens is only consuming 9 watts of power and lasts much longer.   Check out the big box stores for packages of LED bulbs.  The prices won't be as good as the offer Ace had, but these bulbs are now priced where CFLS were a couple years ago.   Check out Menards and Costco for the best deals on multiple packages.    The average family can save over $200.00 per year in electricity if you make the effort and change out your light bulbs. 

*payback can be 3 to 6 months