According to the website about.com, in their Alcohol Cooking Substitutions (http://homecooking.about.com/library/archive/blalcohol6.htm) page, these are listed as substitutes:

Non-alcoholic wine, chicken broth or stock, diluted white wine vinegar or cider vinegar, white grape juice diluted with white wine vinegar, ginger ale, canned mushroom liquid, water. For marinades, substitute 1/4 cup vinegar plus 1 Tbsp sugar plus 1/4 cup water.