How to make custom jquery method accessible from Drupal.behaviors, across multiple javascript files?
I use a slightly different JS pattern with Drupal, which is based on the Javascript Module Pattern.

var FOO = (function(me, $, Drupal, undefined) {
  me.name = "FOO";

  function do_something_awesome () {
  }

  me.do_stuff = function do_stuff () {
  }

  function init (context, settings) {
    me.do_stuff();
    do_something_awesome();
  };

  Drupal.behaviors[me.name] = {
    attach: init
  };

  return me;
}(FOO || {}, jQuery, Drupal));


Anything directly attached to me will be public on the FOO.  The rest is private.  Typically, I will pass in FOO into the closure in dependent libraries.