Of course you don't have time to shop when it's a medical emergency, but you would have time to shop for an elective service or a non-emergency procedure like a hip or knee replacement. 

Aetna already offers such a service to their members enrolled in certain plans. You can go to the Aetna website, enter your zip code and procedure and see a list of providers. For example, a colonoscopy costs $10,000 at Providence and only $2,000 at the Alaska Digestive Center, using the same doctor at either place.

Choosing the cheaper provider saves the employer money (helping keep premiums down) and the patient out-of pocket costs.