<script language="javascript">
function jm(targ,selObj,restore){ //v3.0

  eval(targ+".location='"+selObj.options[selObj.selectedIndex].value+"'");

  if (restore) selObj.selectedIndex=0;

}
</script>

<SELECT onchange="jm('self',this,0);">
 <option value="http://www.google.com.tr">Google Türkiye</option>
 <option value="https://www.r10.net">R10.net</option>
</select>