<script type="text/javascript">      
   divWeHave = document.getElementsByTagName('DIV');      
   replacement = new Array (      
   'Первая замена',      
   'вторая',      
   'третья и т.д.'      
   );      

   numer = 0;      

   for(i=0;i<divWeHave.length;i++){      
   if(divWeHave[i].className == 'forumModer'){      
   divWeHave[i].innerHTML = replacement[numer]+divWeHave[i].innerHTML.slice(16);      
   numer++;      
   }      
   }      
   </script>