I have made yogurt for years. Usually I make 2 gallons at a time. After heating, cooling, and inoculating with the starter yogurt, I have always stuck the mason jars in a cooler with warm water. I always make sure that the water does not reach the lids, as I don't want to chance it seeping in and contaminating anything. Usually, I start in the evening, and let it sit overnight. With raw oatmeal, honey, and bananas, it makes a great breakfast. It also keeps very well. Sunday I opened a jar that I made last November, (hidden in the back of the fridge) although I fed it to the chickens, it smelled completely fine, and I am sure I could have eaten it without any problem.
I have also made the yogurt cheese that MP mentioned, just wrap the yogurt up in a clean rag, and let it drain for about half a day. Really good on pita bread.
We also use yogurt to substitute for sour cream.
It is good stuff! Make some!
Anything we can do ourselves is a step toward independance. Even small steps count!