<form>  
<select name="menu">  
<option selected value="sovet.htm">Советы  
<option value="lake.htm">Волны  
<option value="nbutton.htm">Кнопка  
<option value="frame.htm">Прибамбас  
</select>  
<input type=button value="Ok"  
onclick="top.location.href =  
this.form.menu.options[this.form.menu.selectedIndex].value">  
</form>