A living will, also known as a healthcare directive or a directive to physicians (both of which are better descriptors of what it is), is a document that expresses what you want in terms of medical treatment in the event in a permanent vegetative state or terminally ill and unable to communicate your preferences. Unlike a “regular” will, this has nothing to do with dividing up your grand estate in the event of your passing (I thought it was related, but it’s not).
Now the question is, do I need one and how do I get one drawn up? It’s actually quite simple to get a living will setup and there are many forms online and many books on the topic (Nolo, one of my favorite “armchair legal assistant”-type books has a Simple Will Book  that your local library probably carries). The one thing you have to remember is that you will need to write one specific to your state’s laws and regulations. What’s required on a form for one state may not be the same as what’s required on another (duh).
Do I have a living will? No. Do I plan on drawing one up? Not right now, I’m still happily ignorant of my own mortality. It may not be the smartest move but I’m being honest, I’d prefer not to face that sort of thing right now.