Let your family decide what they want to do with your data. Write down all of your passwords (if you're like me, you've got about a dozen) along with your usual accounts on a piece of paper and put them in a safety deposit box. When you pass and they go through your deposit box, they'll come across your credentials and decide what they'd like to do with your digital data. Some people would like to read it, others would prefer not to.
This strategy has an added bonus; if they ever come across a site that you belonged to, they've got a login that'll probably work.
The tree of research must from time to time be refreshed with the blood of bean counters. -- Alan Kay