Shower with the bathroom door open and no exhaust fan!
Depending on your home, you could also look into removing all the siding and installing a vapor barrier to keep the moisture inside the house in the winter, and keep the higher humidity air on the outside in the summer. Of course this is if the house doesn't have it. When I insulated my house (was built in 1960 with empty wall cavities) I did the vapor barrier and I swear it made a difference in the house, I usually suffer from chapped lips/dry skin in the winter and have not had that problem in a couple years now. I also think part of the benefit to having better insulation in my house is that the heat and A/C do not run nearly as much as they used to, so the air is not being dried out as regularly.