Preposition at the end of a Sentence

So this one time I heard that there was this major english buff or something and he would always correct peoples grammer, even the smallest things that you said wrong. Now admit it, most of us really hate those kind of people because it drives us crazy to have our thought inturpted when the meaning of what we are saying is clear even if we said something incorrect.
So here's the question, this guy said that you should never end your sentance with the word "at". Such as "Where are you at?" or "where do you play at?" So comes the next part of our journey, To the source of all currently known knowlege, The NET! HERE Is a guy who is against it and has two articles saying why it isn't wrong to end with a preposition and uses a few sources as to why the "Rule" is Wrong. HERE Is another explaination which makes a lot more sense. She does call the "Rule" a "Myth" But makes the point that, If the preposition isn't needed and the sentence still makes sense then leave off the preposition, So Going back to my examples "Where are you at?" Really should be changed because it still makes sense to say "Where are you?" But it isn't entirely wrong to end with a preposition, for example "Who were you with?" or "What did you step on?" it just doesn't make sense to leave those words off, or to have them in a different place in the sentece just because it is a rule. "With whom were you?" "On what did you step?" just doesn't sound right and no one talks like that.