Who's going to know if you die? ... family, friends, co-workers - but only if you see them regularly anyway. How about that gal you chat with on-line about the economics of microthermal expansion of Russian Sable toenails?
Here's how it works: You sign up for this and configure it the way you want. It sends you an e-mail however often you want to be "pinged," so that the Deathswitch can make sure you're still kicking. If you don't respond, it goes into "worry mode," and eventually, if you don't respond, it announces to the online world that, yes, you've gone toes up.
There's an interview here with its developer.
20 hours ago