Deathswitch a necessary convenience or just plain creepy?

Last week I heard about a webservice called Deathswitch. Users are prompted to check in and confirm they are “still alive.” If they do not check in after a period of time they are assumed dead or critically disabled and an email is sent to a list of people provided by the user letting them know of said user’s disappearance. Would you sign up for a service such as this? Do you think it is a macabre and unnecessary idea?