Well, I remember The Dord (a winner of a 360) made a thread in which he spoke of how he won and used the odds to his advantage -- but I think it was deleted, magically, as I don't see it in his profile or anything like that.
I think people were saying that if you enter, say, twenty codes into one ten minute slot (that doesn't have a lot of entries as it is), and another twenty in the following ten minute slot (that, too, doesn't have a lot of entires), it doubles your chances -- but I'm not so sure about that actually doubling your chances.
I'm just banking up a large number and unleashing them into a slot with 100 or less entries at an obscure time and day. I think I have 30-some unused. I'll probably wait 'til I have over 50.