<script type="text/javascript">  
$('div.searchForm input.searchSbmFl').before('<label for="GoogSearch">Искать с помощью Google? <input style="height:15px; width:15px; vertical-align: middle;" id="GoogSearch" name="google_search" type="checkbox" /></label>');  
$('div.searchForm form').submit(function(){if($('div.searchForm input#GoogSearch').is(':checked')){window.location = 'http://www.google.com/search?sitesearch=' + location.host + '&q=' + encodeURIComponent($('div.searchForm input.queryField').val()); return false;}});  
</script>