Digital safety deposit boxes: do they exist? if yes, are (any|they) trustworthy?

There are many bricks and mortar financial institutions where one can rent a locked box in a locked room and be assured the contents are secure, that access is constrained and under strict and constant surveillance, and that no one other than yourself and certain named and properly authenticated others will ever have access. It's the traditional place to safekeep things like one's last will and testament, property deeds, family jewels, the map to great grandpap's treasure box under the ol' crooked oak tree, and so on.

Is there a digital analogue? A place to keep one's [master password file](https://security.stackexchange.com/questions/4422/how-to-prepare-for-protecting-identity-after-death/4433#4433) and other digital treasures safe and secure, but available to authorized people upon one's death or other defined circumstances?

*update, 2011-Jun-13* - Here's the central idea presented as a story, provided by this.josh: 

> 
> Alice has some data protected with
>  access controls to maintain the data's
>  confidentiality. Alice has a friend
>  (or family member) Bob. In the event
>  of Alice's death, she wants to pass
>  ownership of the data to Bob. If Alice
>  had stored the data on a DVD and kept
>  it in a safe deposit box, and had
>  written a will specifying that she
>  wanted Bob to receive the DVD after
>  her death. All Bob would need to get
>  access to the DVD would be a copy of
>  the will and a death certificate. 
>  Something that works like this, but 
>  digital.
> 
> 
>