If you have 10-30W oil, you should change to 5-30, or even to full synthetic if temp are real low, because they oil will stay liquid. Your start will be better and your engine will warm up faster.
AND the most effective thing still a block heater, cheap and easy to use with a timer because you need only 1 hour to get the oil warm (less cold....).
I was just thinking the same thing (about winter sucking my mileage away from me... lol)
I actually just ordered an OEM Honda block heater for my car. Hoping that will help a bit with the frost (dont know how much it will do for a lot for thicker ice).
Any type of car cover will help with de-thawing but the car has to be dry before you put it on or you could have a car cover frozen to your car (I had a friend do this once... lol).
I too had thought about a space heater in the car, but could never get past the thought/worry about the car going up in flames if something happened.
I'm thinking about a wintertime WAI on my VX. It should decrease warm up times by some amount... My volvo wagon had a "pre-heat hose." The air filter box has two inlets, cold air from the fender and hot air off of the exhaust mani. It has a spring loaded flapper valve (controlled by a small thermostatic valve thingy) that kept intake temps around 105df all the time.
You (or I) wouldn't have to get a WAI too close, just in the general vicinity of the exhaust mani for warmer air.
Additionally, if you went to a full underbelly pan, you drive train/tranny etc would stay significantly warmer. Just a thought. If you wanted to get really radical you could find a way to re-route your exhaust or a coolant lines back to the drivetrain.