This is a fabulous idea!
If you're too lazy to follow the link...it's an article about a subscription service called E-Mealz that provides a week's worth of dinner menus based on that week's grocery store sales. They currently only offer menus based on Wal-Mart, Kroger, ALDI, Ralph’s and Publix grocery chains. And only $5 a month (less than many other similar services). In a family context, I'm sure the service would easily pay for itself. There's even a forthcoming "app"!