It should be a good idea to have some mechanism to request to the user who asked a question to mark the question as resolved. I know not all questions are resolved but some of them a lot of times are clearly resolved and the answer is still unmarked.
I'm talking about not only a reminder like the people asked for at Reminder to mark question as answered, I'm talking about some kind of button that can be pushed by other users who think the question is clearly resolved and if an important number of users (this is the more difficult point... to determine how many is needed to do this) click on that "ask for a resolved mark", the question must be marked as resolved on any answer or a consequence can happen. This consequence could be the loss of some reputation points or something like that.
It's only an idea that must be polished. What do you think?