The 'death clock' is a (not so) subtle perspective on a deep ethical problem: should we know how much left we have of our lives? The implications of having this knowledge could be huge and could have a great impact on our life. The idea came while browsing Pro Link Directory, a SEO-helping machine (but now I'm digressing...).
We're not going to discuss the religious aspects of predestination. Instead we assume a more pragmatic approach: would it be ethical to disclose the death date to a person, given that you would have the means of obtaining it (call it an oracle for now). Even further, would you ask the oracle for your death date?
The fundamental question here is whether the effect of having access to your 'death clock' would be beneficial or not and quite possibly there is no one answer to this question. People may react positively and use the time left to enjoy more their life and friends, plan and finish all projects (see the Bucket List). Other may be left paralyzed in face of fatality.
The five stages of grief would likely characterize a person's state after finding that he is running out of time. Wheter they can accept, deny or remain depressed by the ticking clock fundamentally influences the effect of the news.
People rarely think they will eventually die and still this is the only fact of life. And most likely, this is essential for a healthy, fulfilling life.