Generally, someone is given legal standing to take care of these things, like an executor of an estate.
Even if they didn’t, e-mail and blogs tend to expire if inactive too long and a website has both hosting and domain registration that has to be paid for. I’d assume they’d be terminated for non-payment.
If there was no will and no specific mention of any blogs, emails or websites, then most likely nothing will be done about it.
You could possibly contact the site owner and ask them to take the account down, after explaining the reason. Same with social networking. If you ask them nicely, I’m sure they’ll be happy to take down the account.