I'm not a snow person either, but I did see something on TV a while back comparing some different solutions. A typical front wheel drive car drives into a snow drift and gets one its tires stuck. The driver spins the tire a bit, trying to drive out, melting the snow and letting it refreeze into a slick icy rut. The tire then just hopelessly spins in the rut as all the engine power goes to that one wheel.

As a demonstration, they tried various methods to get unstuck, like shoveling a path out, floor mats, kitty litter, trying to melt the ice with the cigarette lighter, etc. A hunk of chain link fence is one thing, but for the typical things that people might put under the tire, they were all basically ejected out the back and the tire just spun in place. The lighter is useless and just makes more ice. I forget why digging the path didn't work...I think the tire still couldn't initially get out of the iced up rut it was in and the "lip" of the rut was too hard to break up with the plastic snow shovel. Well, what was the secret to getting out?

Reducing the tire pressure so that you increased the surface area in contact with the icy rut. Then some gentle application of throttle and the car climbed right out of the rut. You can keep driving at a safe speed until you're on firmer ground, and then you can stop to reinflate the tire. You did remember to pack the portable compressor, didn't you? <img src="/images/graemlins/wink.gif" alt="" />

I think this method works partly by increasing the friction on the stuck wheel, so that it can help climb out of the rut. And I think the added friction helps send power to the non-stuck wheel, which also helps pull the car out. Someone who understands automobile differentials can explain that part better than me.

With an open differential (what most passenger cars have) the power supplied by the engine will take the path of least resistance. More specifically if one tire has traction and the other does not, all of the engines power will be sent to the slipping tire and not to the tire with traction. Airing down tires in snow, mud, sand, etc, will greatly increase traction by giving the tire a larger surface area on the ground. If you get stuck in a situation where one tire has traction and the other does not, airing down the spinning tire may help to balance out the power distribution a little. However, once you are un-stuck, you should air down the other tire as well. Airing down, in some situations, can almost provide as large of a traction gain as shifting into 4wd.


How dirrentials work: http://auto.howstuffworks.com/differential.htm
Airing down: http://www.californiajeeper.com/tire-presures.htm

Yep, thats the problem, a differential will send all power to the wheel with the least amount of traction. A lot of the AWD systems have this problem too.
Sometimes you can power brake it, push the brakes a little bit (or parking brake if rwd) and the spinning tire will get stopped by the brake first and transfer some power to the other. Some people who offroad 2wd's will hook up two parking brake pedals, one for each side.
Some traction control systems do this by using the ABS pumps to apply the brakes to the faster spinning wheel to get power to the others. This of course eats brakes.
I've had all types and your much better off with the traditional rwd with locking transfer case in the middle that way there is no slipping between the front and rear. Those can also help prevent wheel lock ups by downshifting and using engine braking when coming to a stop rather than applying brakes and letting the ABS release your brakes when one wheel starts to slide.
Years ago I have a little 4 cylinder 4x4 Chevy S10. Very light truck and of course all those people who think rwd can't go in the snow didn't understand how I got around, I rarely needed to put in it 4wd. Late one night a big storm hit and a highway overpass with on ramp froze up. To get on the highway I had to go up the hill and on top get in the left turn lane then start down the other side and stop at the light and wait for it to turn green before making the left turn on to the on ramp. The police were there directing traffic as everyone who tried to stop at that light couldn't and would just slide on through so the police would stop the traffic the other directions so no one would get hit. I saw them as I got came to the top of the hill motioning someone who hadn't gotten into the long left turn right away to go straight so I got in the left turn lane before they could motion me to go striaght. I pulled the 4x4 lever just to be safe and downshifted as I got closer to the light and the police stopped traffic as the vehicles in front and beside me started sliding. They looked at me with big eyes as I downshifted again and came to the stop bar and applied a tiny bit of brake and stopped like normal, then motioned for me to go on since they already had traffic stopped the other ways. I popped it out of 4x4 and started off and drove around the turn and onto the highway without any problem. The locked 4x4 won't let one of the wheels brake loose since one of the wheels at the other axle would have to do the same but it still had traction. Years later driving a newer AWD vehicle with ABS I tried to slowly stop at a light on flat ground in the snow. One wheel slipped a bit and the ABS kicked in and release the brakes and I had to go on through as the older ABS systems had a couple second release/apply cycle and the viscous coupled front and rear allowed a speed difference between the front and rear axles.
Some vehicles even with auto transmissions you can start in 2nd like a manual to get less torque to get you started in low traction.

She hit the gas too hard, but thats how most people do anyway. If your transmission will let you start in a higher gear, higher gear=less torque=less chance to break traction. Then apply the gas very gently, if it breaks loose let up on the gas. Most accidents happen because people hit the gas harder when they loose traction.