This article is from the Miscellaneous Cat Information FAQ, posted to rec.pets.cats newsgroup. Maintained by Cindy Tittle Moore with numerous contributions by others.
During winter or other dry seasons, cats may pick up static and discharge it every time you pet them. One solution is to rub them with a fabric softener sheet. The chemicals in fabric softener are not a problem for cats, although some of the more heavily-scented ones may be objectionable to the cat.
Some people invest in humidifiers for the house, and that reduces the static in a cat's fur as well.