Jenny Sabo, of Sabo Family Farm, told me how to make my own yogurt; her version is much simpler than anything I have found on the internet, and less intimidating. I've made it once now, and it turned out runnier than the store-bought version, but tasty enough that my kids drink it for breakfast. They particularly like the batches we added raspberries to - it is a ready-made smoothie that covers all the things I require them to eat for breakfast, without any thought on their part. We added chokecherry syrup to one batch and maple syrup another; I'm planning to use some of the plain yogurt to make a dill-yogurt dip for smoked salmon. I'm looking forward to trying other flavorings in future batches, especially some odd ones like candied ginger.
Jenny's Easy Yogurt:
Warm 1 gallon of milk, preferably unhomogenized, on the stove until you can just leave your finger in the milk for a count of 10 seconds (this comes out to 110 degrees). Remove half a cup of milk and mix 2-3 tablespoons of a plain yogurt you like into it (the yogurt works as a culture to start the fermentation). Pour the milk and yogurt into the pot and stir well to mix completely. Place the pot in a cooler, wrap the cooler in blankets, and let set for 24 hours. The yogurt can then be spooned out into containers and stored for a week or two; add flavoring now so it doesn't interfere with the setting up.