• A living will is a legal document that enables you to declare your wishes to receive or to have withheld life support procedures when permanently unconscious or terminally ill and unable to make informed decisions. Living wills also are referred to, in some states, as a health care declaration or health care directive. A good example of why it is so important to have this document in place is the Terri Schiavo case.
• A durable power of attorney (POA) for health care is a legal document in which you designate a trusted individual—your "agent"—to make medical decisions for you when you are unable. Do not confuse this with a financial power of attorney, which authorizes someone to make financial decisions for you when you are incapacitated. The POA can grant broad or specific powers to the agent. In your POA you can specify the treatments you would or would not want to receive.
• A do not resuscitate (DNR) order sometimes supplements advance health care directives. Placed in a patient's medical chart, a DNR is usually used by people who are already critically ill and feel strongly against use of life-prolonging measures.

Now it is not my intention to give anybody legal advice, but to jump start your thoughts on these issues. For more information, a great resource is the American Bar Association's page on frequently asked questions about estate planning.