Use custom checkboxes instead of wonky browser ones

fancyCheckboxes.js

(function($) {
  $.fn.fancyCheckboxes = function() {
    return this.each(function() {
      var input = this;
      $(input).hide();

      var fancy_checkbox =
        $('<span class="fancy_checkbox"/>')
          .addClass(
            $(input).attr('checked') ? 'checked' : ''
          )
          .on('click', function(){
            $(input).attr('checked') ? $(input).attr('checked', false) : $(input).attr('checked', 'checked');
            $(this).toggleClass('checked');

            $(input).trigger('click');
          });

      $(input).after(fancy_checkbox);
    });
  };
})(jQuery);    

Looks pretty good to me.

Of course, I've always got thoughts. Here are a few:

1. I've had trouble in the past unchecking checkboxes by setting the checked attribute. The method I've used with success was $(input).removeAttr('checked'). However, this may have changed since I last dealt with that.
2. You could save a lot of duplication by setting var input = $(this) and changing all instances of $(input) to just input.

Looks handy. I'm with amiel when it comes to setting input = $(this), and avoiding the repeated calls to the jquery wrapper. It cleans things up visually and also saves some cpu cycles. I've had no experience with setting checked attributes programatically, but it does seem like removing the attribute entirely makes the most sense here.