What LFP said, plus 5 dogs. Well, they're not cheap, but they work pretty good as heaters when I lay down in bed and they all plop down around me. :lol: Doesn't usually get all that cold here, down to maybe freezing but usually no less than 35-40F at coldest before dawn. Right now (1230am) it's 42F outside, and about 62F in the bedroom with the dogs, myself, and the computer. Rest of the house tends to drop down to maybe 10F above whatever outside is, but that's because I tend to leave windows open to air out the doggie odors. :lol: (unless it's raining or it's REALLY windy) Daytime is usually 55-65F in winter, sometimes more, and with the front door and windows open and unblocked (facing south) I can get the front room to 75-80F if it's sunny and not windy.
During winter I open up the house when it is warmer outside than inside, and once it gets colder outside than inside I'll close it back up. I do it the other way around in summer. Sometimes when the wind is too still for this to move air thru the house, I will use a fan in a window at one end of the house and open the other end up, to suck air thru the house from whatever part of the outside is the temperature I'm after (front yard in winter, back yard in summer).
When I need to heat a different room to work in, mostly I just get all the dogs in there, plus me and whatever tools and whatnot I'll need, and any electronics I think I'll use, set it up and turn stuff on. Close the room off, including foam blocks in the vents, and blankets in the windows and along the door edges, to keep all the heat in there. Setup the laptop to browse ES, web, videos, or reference notes/etc. while warming the room with our body heat and stuff, and in an hour or two it's at least 65-70F, even if it had been 50F before. Also I'll use incandescent lights when trying to keep a room warm, instead of CFLs/etc., because it's not waste heat at that point.
I also hang blankets between rooms anyway, summer and winter, to keep heat where i want it (out or in), as well as along walls and windows and any doorways. Trapped air between the blankets and the walls seems to help a fair bit in keeping heat in it's place. Multiple layers can be necessary sometimes.
But it can certainly help keep the electric bills down--last month it was only $44.84. Even in the worst of summer when I have to use a window AC unit or the main house swamp cooler I can usually keep it under $150, sometimes under $100, when my crazy sister isn't around to waste power and leave doors and windows open at the wrong times.
Better think through that again, I guess! 
