When I first moved into my house our gas bill was $100 per month. This was rather high to me since i had just moved here from Southern California. I am now told that $100 per month is actually rather cheap for where I live.
I still wasn't content though, and I was rather sick of hearing the furnance kick on so many times per day.
I went to my local hardware store and purchased an electronic thermostat. It is able to be programmed to four programs during the week, and four programs during the weekend. I put the same program on weekdays/weekends, and it looks like this:
5:00am - 65 degrees (Wife wakes up for work at 5:30 and I want it to be warm for her)
7:00am - 60 degrees (I kept it warm a little longer for my benefit)
4:00pm - 65 degrees
10:00pm - 60 degrees
I don't mind the cold as much as she does, so I just put on a sweater and thick socks while I work.
Before the electronic thermostat we kept our thermostat to around 67 degrees (or was it 70?) all day.
Now that this little puppy is installed our monthly gas bill went from $100/mo to $60/mo. During the summer our gas bill is around $13/mo for heating the water, so that means we consume about $47 worth of gas per month to heat the home.
I admit, it gets a bit cold and I'm sure my wife would like it to be turned up a bit. Maintaining a 70 degree house though is next to impossible without paying excessive bills.
Some thermostats have an adjustable heating cycle (sometimes called anticipation). You can get further improvements in your gas powered furnace if it is an older model, by reducing the heat cycle length. The furnace heat exchangers will saturate with heat in 2 minutes, then can only absorb about 15% of the heat produced by the burners. 85% of the heat produced after the saturation point goes up the chimney. By shortening the burn cycle and keeping the fan blowing while the burners are off, you increase the furnace efficiency.