<script type="text/javascript">
function Show(selectedIndex)
{
var cnt = document.getElementById('country')[selectedIndex].text;
alert(cnt);
}
</script>
<select id="country" size="1" onChange="Show(selectedIndex);">
<option value="1">Страна 1</option>
<option value="7">Страна 2</option>
<option value="15">Страна 3</option>
</select>