当月を選択しリストの最初に表示する 　　　　　
Sample
ソース 
<HTML>
<BODY>

<SCRIPT LANGUAGE="JavaScript">
<!--
var time = new Date();
var month = time.getMonth();
var date = month - 12;
var realMonth = month;
var future = month;
month = month + 1;
document.writeln ("<FORM><SELECT>");
do {
  month = date;
  if (month >= 12) {
    month = month - 12;
  }
  if (month < 0) {
    month = month + 12;
  }
  date++;
  var dateName ="";
  switch (month) {
  case 0:
    dateName = "　１月";
    break;
  case 1:
    dateName = "　２月";
    break;
  case 2:
    dateName = "　３月";
    break;
  case 3:
    dateName = "　４月";
    break;
  case 4:
    dateName = "　５月";
    break;
  case 5:
    dateName = "　６月";
    break;
  case 6:
    dateName = "　７月";
    break;
  case 7:
    dateName = "　８月";
    break;
  case 8:
    dateName = "　９月";
    break;
  case 9:
    dateName = "１０月";
    break;
  case 10:
    dateName = "１１月";
    break;
  case 11:
    dateName = "１２月";
    break
  }
  month++;
  realMonth++;
  document.write ("<OPTION value=\"" + realMonth + "\">" + dateName + "");
  realMonth++;
}
while (date < future) document.write ("</SELECT></FORM>");
//-->
</SCRIPT>

</BODY>
</HTML>
ワンポイント解説
dateName　が、リストに表示される文字列です。