I have spotted many questions that have an answer that solves the problem, but the answer has not been "Accepted" by the questioner. This is either because he doesn't know that he has to do it, or because he just wants to solve his problem and doesn't care.
I thought that it would be a good idea to give the privilege to users with more than (e.g.) 5000 reputation to be able to accept answers in questions on their own will, after (e.g.) 5 days, if the question has clearly been answered (and stated as solved by the questioner) but the answer has not been accepted (and thus the user that answered has not been granted the reputation he deserves).