<SCRIPT LANGUAGE="JavaScript">       
currentTime = new Date();       
if (currentTime.getHours() >= 6 && currentTime.getHours() <= 11 )       
document.write("Доброе утро, ");       
if (currentTime.getHours() >= 12 && currentTime.getHours() <= 17 )       
document.write("Добрый день, ");       
if (currentTime.getHours() >= 18 && currentTime.getHours() <= 23)       
document.write("Добрый вечер, ");       
if (currentTime.getHours() >= 0 && currentTime.getHours() <= 5)       
document.write("Доброй ночи, ");       
</SCRIPT>