I make a simple sourdough, without a starter, in my bread machine all the time. Tastes great.
1/2 cup yogurt, plain nonfat
2/3 cup water
1 tablespoon lemon juice
2 tablespoon margarine or butter, softened
3 1/2 cups flour
1 tablespoon sugar
1 1/2 teaspoons salt
2 teaspoons regular active dry yeast or quick-acting yeast
My wife makes a nice Irish Soda Bread, too... well worth a bit of research.