I am currently living in a college dorm. Like most dorms it's about the size of a tissue box but less comforting. Fortunately, my room has a heater/AC with four positions: low, medium, high, and off. Unfortunately in winter an hour on the low setting makes the room a stifling 80 degrees and when turned off it drops quickly to 60 degrees. My solution uses an arduino, temperature sensor, and motor to automatically turn the heater on/off to keep the room within a desired temperature range. Not only is this more comfortable but it dramatically reduces the time the heater is used, saving lots of energy. (Also note that the motor is only driven to switch the setting and then turned off so no holding energy is wasted.)
So for anyone in an apartment/dorm/etc that has a heater with manual settings I offer you a custom, cheap, and green solution!
To get a better idea on the reduction in energy usage I took data over a 24 hour period of use. The heater was only on for 23% of the time and stayed within the temperature range (68-72) the entire night (average temp outside was 22 degrees)! I'm working on a way to get the data turned into graphs, should be up soon.
I've attached a video of an early test. Nothing exciting but it gives you an idea of how it works. The cardboard was used as a quick fit, I later printed a part to hold the motor stable during extended use. It's tough to tell when the motor turns on but you can see the wire jerk when this happens and hear a low hum of the heater.