[ZoNT]

<select id="s1">
<option>123</option>
</select>
<input type=button onclick="addfild('s1')" value=add />
<script language=javascript>
function CreateOpt(value,text) {
var opt = document.createElement('option');
opt.value = value;
opt.text = text;

return opt;
}
function addfild(id) {
  var select = document.getElementById(id);
  select.options.add(CreateOpt(1,',bla-bla-bla'));
  select.options.add(CreateOpt(2,',bla-bla-bla 2'));
}
</script>