A few years ago, I came across a Taylor newsletter that had a good article on guitars and humidity. I don't recall what issue of the newsletter this was in, but I imagine you could find it through Taylor. After reading this article, I started using a humidifier, one made out of surgical tubing that you soak in water for a few minutes, wipe off and then place in the sound hole. I've noticed my guitar tends to require less tuning since I started using the thing, particularly in the winter when indoor humidity around here is low. But I once forgot to take it out: as I stopped playing to remove it, somebody in the audience yelled, "Oooo, look! It's got a tapeworm!"