[StavrosK]

That's what http://www.deadmansswitch.net/ (disclosure: I wrote it) does, it also has configurable intervals so you can make them as short or as long as you want. It sends you an email every interval, and, if you don't reply to any of them, it sends your messages.

[sitkack]

Can I have copies of all the user submitted data? Probably full of bank account details, safe combos, etc.