Create an Array with n values that is able to use Array methods instantly
As the comments already say, I'd not put too much into such a function, that is, IMO creating the array with initial size and elements is probably enough to make a difference.

Array.create = function (n, initial) {
  var result = new Array (n);
  for (var i = 0; i &lt; n; ++i)
    result[i] = initial;
  return result;
};

// Array.create (3);
// Array.create (5, "hi").map (...);


Which also could just be a regular function makeArray or so I guess. So you get one benefit without the rather cryptic calling convention (mapCB/method) you have at the moment. Sure, it's a matter of opinion, but I had to take a moment to understand what that is supposed to do, so arguably that is not a good choice if you want other people to read that later.

And good point about the apply, I wouldn't want to see that in real code as well.