Last summer I made my first batch of sourdough bread using wild yeast. The recipe for cultivating the wild yeast used a boiled potato mashed into flour, water, and sugar. This goop was then put in my (turned off) oven to stay warm and ferment for three days.
I've revisited this recipe after reading about wines that start their fermentation solely with the yeast that is already on the grape skins. This took me back to another article, this one from Anthony Bourdain, who talked about the best bread he ever had was started with a mother fed with grape must. The "mother" is the sourdough starter. A cup or two of well-nurtured starter will enhance the flavor of any yeast bread. It won't do a lot of work in making the dough rise, so you'll still add commercial yeast.
So last night I took a medium sized cluster of grapes and mashed them into 1 cup of wheat flour, 1 cup rye flour, 1/2 cup sugar, and 1.5 cups of water. I'm not supposed to get much bacterial action for 2-3 days, but I did just noticed a cluster of bubbles beginning to foam at the surface. Hopefully this is a bellwether of tasty things to come! Until then, this starter is going to stay cozy on top of my radiator.