I am. Why not? As has been said- when the time comes that your organs may be called upon, you're a slab of meat. You're no longer a living human being. Your body may function but, without the brain, you are just a pumping heart, a breathing lung, etc. I know there are some religions where it's not allowed to do this sort of thing, and I can respect that if those are your beliefs. But, for everyone else... why not?
Even if you wrestle with issues of "more or less deserving" or "deserving at all", here's the thing: they're already on the list. They're going to get the part they need from someone. Let's say we have two people who need a heart. One you'd say is "deserving", and the other is not. Even if the "not deserving" person gets your heart, in this horrible hypothetical, that still brings the "deserving" person one step up the waiting list, one heart closer to life. So... even if you must insist that "undeserving" people are on the lists, think of the ones who really, truly need them. Again, YOU are done using them, just pass them on to someone who CAN use them.
Doctors are bound by law, the hippocratic oath, their licenses, and all the basic tenets of ethics and morality to continue to save your life until you're dead. They must do everything in their power to keep you from dying, and "letting" you die is simply not something that happens.
I hope this thread takes away the uncertainties some people have had, and can result in some extra donors in the future.