My preferred pattern for jQuery plugins.

hoverzoom.js

// A simple plugin which zooms the element when it's hovered:
//     $("a").hoverzoom();
// Demonstrates my preferred pattern for building jQuery plugins.

$.fn.hoverzoom = function() {
  var method = arguments[0] || "init";
  var parentArgs = arguments;
  this.each(function() {
    var args = Array.prototype.slice.call(parentArgs);
    args[0] = $(this);
    $.fn.hoverzoom[method].apply(null, args);
  });
  return this;
};

// Note the explicit "self", removing any need to fiddle with "this":
$.fn.hoverzoom = $.extend($.fn.hoverzoom, {
  init: function(self) {
    self.on("mouseenter mouseleave", function(event) {
      self.hoverzoom("toggle", event.type == "mouseenter");
    });
  },

  show: function(self) {
    self.stop().animate({
      zoom: "200%",
    });
    self.data("hoverzoom-last", "show");
  },

  hide: function(self) {
    self.stop().animate({
      zoom: "100%",
    });
    self.data("hoverzoom-last", "hide");
  },

  toggle: function(self, showhide) {
    if (showhide === undefined)
      showhide = self.data("hoverzoom-last") == "hide";
    self.hoverzoom(showhide? "show" : "hide");
  },
});