I bring mine into my basement for the winter. I sprinkle a little water on the every month til it's time to bring them out again. They will droop a little inside and the blooms will fall off, also they will turn a light green in the stem. It's all good. When you take them back out trim off any dead or dehydrated stems also.

My mother hung them upside down (also in the basement, like Plantfreak!) for many years. She just shook excess soil off the roots, and used a piece of string/hung from the rafters in a semi-sunny area.
Now however, she just leaves them in their terra cotta pots, waters slightly during winter, and places them anywhere in the house that there's sun. Heck, some even bloom during the winter (small blooms), and some of her geraniums are 8-10 years old!

Courtney