I' ve always had real good luck using a crow call. I think the key is not to over use it. I do as another turkey hunter told me once. Hunt the crows. I like to give a few location caws then start with maybe one fight call. This will usally get the neigborhood crows awake and have them zooming around looking for the crow that is mad. As they do all the cawing and looking I listen from a good vantage point.

Now I' ve been sitting quietley ontop of a ridge watching other hunters work a logging road before. They cawed and cawed and no gobbles and no crows. As soon as they left, I gave a fight caw and a hawk whistle... G-O-B-B-L-E!!