From CBS Healthwatch:

Medical discount programs offer a unique alternative to the high cost of health care. These programs reduce the cost of medical services through pre-negotiated rates with various medical service and equipment providers. These providers include pharmacies, optical and hearing service providers, dentists, and chiropractors.

People who may benefit from using a medical discount program to reduce out-of-pocket expenses include:

• Individuals with insurance plans that do not provide coverage for certain items or services
• Individuals with high-deductible health plans and/or medical savings accounts
• Medicare recipients
• Individuals with no insurance coverage

Each medical discount organization offers a unique mix of medical services, discounted rates and pricing. Discounts range from 5 percent to 60 percent, depending on the type of service purchased, with an average range of 15 percent to 20 percent off standard medical prices.

USA Today - Hospitals sock uninsured with much bigger bills

Kaisernetwork.org - Daily News Summaries of Health Policy

USA Today - Hospital bills spin out of control

USA Today - Medical costs prove a burden even for some with insurance