Perhaps the most unusual WordPress plugin I’ve ever heard of is Next of Kin. According to the plugin’s creator:
It monitors your own visits to your wordpress system, and will send you a warning email after a number of weeks (of your choice) without a visit. If you fail to visit your blog even after that, the system will send a mail you wrote to whoever you choose.
Presumably, the idea is to include the access credentials for your site(s) in the final email.
This raises the more general question of what should happen to web content after a person dies. Facebook pages can be turned into memorials. Blogs can be left up, intentionally taken down, or left to eventually vanish from non-payment or some other hosting change. What is most appropriate generally? What would readers want for themselves?
Email might be the trickiest of all. Most of it is trivial, but some is an important life record. Should any of it ever be passed along to survivors, as a person’s personal correspondence might once have been?