$.fn.spin = function(speed_word){
  moz = $(this).css('-moz-transform');
  webkit = $(this).css('webkit-transform');
  already_rotating = ((moz != 'none' && webkit == '') || (moz == '' && webkit != 'none'))
  var number = 0;
  var speed = 0;
  if (already_rotating){
    return false;
  }else  if (speed_word == 'silly-fast'){
    speed = 3;
  }else if (speed_word == 'fast'){
    speed = 0.3;
  }else if (speed_word == 'slow'){
    speed = 0.1;
  }else if (typeof(speed_word) == 'number'){
    speed = speed_word / 10;
  }
  var self = this;

  setInterval(function(){
    number += speed;
    jQuery(self).css('webkit-transform', 'rotate(-'+number+'deg)');
    jQuery(self).css('-moz-transform', 'rotate(-'+number+'deg)');
  }, 50)
}