This is an extension of the question 'What to do with original posters who don't accept correct answer'
I have seen a few new users who have had an issue and used this site to get their answer, after they have the answer they are not seen again, and leave the questions without accepted answers.
Could we implement a system where moderators can accept the answer with the most up votes after a month, or failing that as the majority are not always correct, could we force accept an answer when the OP posts a comment saying that the answer was correct but has not accepted it. Such has happened here