I've long thought of a start up that would offer a kill switch service. Something that you checked into every so often to verify you were still alive (by email, text, or it just monitored your social feeds). If over a custom set period of time 30-365 days, if it hadn't heard anything it would attempt to confirm you're still alive either by notifying you directly or a friend to confirm if you weren't. At which point it will notify services to suspend accounts, or send a list of passwords or account access information to those you trust to handle deactivating your facebook, twitter,or turning it into a memorial of sorts (since I guess your social feeds kind of become a digital memorial of your life). The killer feature even possibly delete sensitive data you don't want relatives seeing on your computer by installing some client app. :P

I don't know I'm surprised a kill switch service like this doesn't exist.