I'm not sure how well liked this idea would be, which is why I've held off posting it til now, but I'd imagine there's some way we could check for and compile a list of users whose journals have been idle longer than a certain amount of time. We could then contact them via email (since they had to have a valid email address when they signed up,) asking if they'd like to continue journaling, or if they'd forgotten and would like it deleted. I can see it being easy to put in a mention about paid accounts, too.
I can see a lot of reasons this would be good, more available usernames for new users (lots of people will just give up if they can't get the first or second username they try,) people checking out random journals are less likely to find only blank ones, we'd have a more active community. Downsides, removing a journal before someone can get back to us about keeping it, etc.
I don't know, I think with enough people discussing this, we could work it out so it works well, but I can see us being fine without doing this. I just wanted to bring it up.