Try to have a neighbor come by with their car, and use jumper cables. The running car will have enough juice to let you crank the engine over if it's just a bad battery. Then you'll know where to drive when you get it started, to Sears for a new DieHard <img src="/images/graemlins/grin.gif" alt="" /> If jumping it doesn't work, then you probably have another problem. The idea about keeping the terminals and cables clean is vital too.
I carry jumper cables in my vehicle, and have a set in my wife's car, so someone could help her if needed. I also have one of those jumpstart packs, which I have never used on my own car, but, have used several times on other people's cars in our work parking lot. They are surprisingly powerful for a short time.
Also, your charger may have a "jump start" setting. Some of them can briefly deliver a lot more than just charging current.
You could get a block heater, in some cold weather areas it's standard gear.
Best of luck!