<div style="display:none;" class="nav_up" id="nav_up">
  <img alt="↑" width="32" height="32" src="http://we6.ucoz.com/img_script/up_str/2_u.ico" > </div>
  <div style="display:none;" class="nav_down" id="nav_down">  
  <img alt="↓" width="32" height="32" src="http://we6.ucoz.com/img_script/up_str/2_d.ico" > </div>
  <script>
  $(function() {
  var $elem = $('body');
   
  $('#nav_up').fadeIn('slow');
  $('#nav_down').fadeIn('slow');  
   
  $(window).bind('scrollstart', function(){
  $('#nav_up,#nav_down').stop().animate({'opacity':'0.2'});
  });
  $(window).bind('scrollstop', function(){
  $('#nav_up,#nav_down').stop().animate({'opacity':'1'});
  });
   
  $('#nav_down').click(
  function (e) {
  $('html, body').animate({scrollTop: $elem.height()}, 800);
  }
  );
  $('#nav_up').click(
  function (e) {
  $('html, body').animate({scrollTop: '0px'}, 800);
  }
  );
  });
  </script>

.nav_up{
  padding:2px;
  position:fixed;
  width:32px;
  height:32px;
  bottom:20px;
  opacity:0.7;
  right:30px;
  cursor: pointer;
  }
.nav_down{
  padding:2px;
  position:fixed;
  width:32px;
  height:32px;
  bottom:20px;
  opacity:0.7;
  right:66px;
  cursor: pointer;
  }