Using the Unanswered tab, I was surprised to find a large number of questions that were already answered in the answer box, correctly, and thoroughly. But if the answer(s) is never upvoted, the question remains in the tab where it does not belong. To make things worse, the Community user occasionally bumps such already-answered questions to the front page, wasting the screen real estate.
By now I've read a number of such answers (to make sure they are indeed correct) and subsequently upvoted: this is by far the easiest way to reduce the number of Unanswered questions on the site (currently 8409). Of course, 30 upvotes per day only go so far, which is why I write this, hoping that more users will find a little time for this kind of clean-up.
Why so many question owners do not upvote correct answers to their questions, I have no idea.
As an aside (but in line with the topic), I'd like to recognize J.M. as the first MSE user to vote 10000 times.