Yes I have completed the organ donor card and also have put it in a living will. As Mickeyfan1 stated, just telling your family is not enough because if they say no, no matter what you want, it won't happen. I know that most people would like to think that their family would honor their wishes, twice I have known people who decided not to for their own reasons...usually shock and grief at the time (one seriously regrets it now and has to live with the regret of not honoring what her mother wanted).
You do not need to see a lawyer for a living will..you can do it yourself and have it notorized. And the living will also covers other issues besides organ donation...such as power of attorney, life support etc. so they are a good thing to look into.