Who owns your Social Media Property when One is Dead?

I mean with the reliance on social media and the impact of social media in our lives today and the future ongoing, is it not safe to think about this now, Who owns your Social Media Property when One is Dead?

e.g Who owns your Facebook, Twitter, Yahoo, Google+, Emails, MySpace and others

I mean your Pictures, your important emails, your write-ups....who ...?

Have you ever thought about this, what do you think?