s_date = new Date();

function writeimage() {
   // Sunday Image //
   if((s_date.getSeconds() % 2) == 0){
      document.write('<a href="http://www.buriedtreasurechest.com/cgi-bin/chamberredir.cgi?a=webbuilders"><img src="http://www.buriedtreasurechest.com/img/WebbuildersBannerAd.gif" /></a>');
   }
   // Monday Image //
   if((s_date.getSeconds() % 2) == 1){
      document.write('<a href="http://www.buriedtreasurechest.com/cgi-bin/chamberredir.cgi?a=desmond"><img src="http://www.buriedtreasurechest.com/img/desmondPuller.gif" /></a>');
   }
}