Very timely.
I was just downloading a Will To Live provided gratis by the National Right to Life people, found here: http://www.nrlc.org/euthanasia/willtolive/index.html
and as I did so, I reflected on the fact that the reason Michael Schiavo got away with this is that Terri could no longer talk in complete sentences.
"THE WILL TO LIVE Protects your own life and the lives of your family members when you cannot speak for yourselves."
You better check the wording out carefully with a lawyer. Depending on the state you are in the notion of 'extraordinary measures' will mean different things. In some states food and water is considered an extraordinary measure. Some very sick people have found this out, unfortuantely.