I think something should be done with the homework questions: there are too many of them now. I suggest that one reason for closing should be "homework". If at least 3 people vote for that reason to close, the question should be deleted immediately. I suggest to have also a visible sign on the front page for newcomers (right before they register) that this site is not for homework questions.
Let me make a suggestion which seems obvious to me: You should only vote to close a question as homework if you can solve it. By this I mean you have actually thought through most of a solution, not that you think "oh yeah, I could probably do that." Both here and on math.SE, I frequently see questions attract closed votes because they are formatted like homework questions, but they are actually substantially harder.