Sorry for the belated update, but the crockpot yogurt experiment turned out well! It is a little thinner than store-bought yogurt but it tastes delicious. I have two containers of yogurt in my fridge right now: one plain, and one with berries. To make the berry yogurt I just defrosted some frozen berries in the microwave and stirred them, along with a little honey, into some of the yogurt.
Then I poured it into a container to keep in the fridge. Beautiful!