In addition to your academic record and recommendations, the essay can can push a borderline applicant into the "Admit" column, if executed properly. That's the purpose of my post today -- to help you write the best essay you can. So it's time to start thinking about this, if you haven't already done so.
You will most likely be using the Common Application for at least some (if not all) of your target schools. Chances are, even if you don't end up using the Common App (unlikely), you will still need to write an essay on a general topic such as those that the Common App requires.