<input type="button" value="excel (IE only)" onclick="startExcel();">
<script language="javascript">
function startExcel() {
 var xls = new ActiveXObject ( "Excel.Application" );
 xls.visible = true;
 var newBook = xls.Workbooks.Add;
 newBook.Worksheets.Add;
 newBook.Worksheets(1).Activate;
 newBook.Worksheets(1).Cells(1,1).value="First Column, First Cell";
 newBook.Worksheets(1).Cells(2,1).value="First Column, Second Cell";
 newBook.Worksheets(1).Cells(1,2).value="Second Column, First Cell";
 newBook.Worksheets(1).Cells(2,2).value="Second Column, Second Cell";
 newBook.Worksheets(1).Name="WorkSheet from Javascript";
 // newBook.Worksheets(1).SaveAs("C:\\temp\\TEST2.XLS");
}
</script>

HKEY_CLASSES_ROOT\CLSID\{0002E541-0000-0000-C000-000000000046}
"Microsoft Office Spreadsheet 10.0"

<object
width = 900
height = 500
id = 'excel'
classid = 'CLSID:0002E541-0000-0000-C000-000000000046' VIEWASTEXT>
<param name=DisplayTitleBar value=true >
<param name="DataType" value="CSVURL">
<param name="AutoFit" value="0">
<param name="DisplayColHeaders" value="1">
<param name="DisplayGridlines" value="1">
<param name="DisplayHorizontalScrollBar" value="1">
<param name="DisplayRowHeaders" value="1">
<param name="DisplayTitleBar" value="1">
<param name="DisplayToolbar" value="1">
<param name="DisplayVerticalScrollBar" value="1">
<param name="EnableAutoCalculate" value="0">
<param name="EnableEvents" value="0">
<param name="MoveAfterReturn" value="1">
<param name="MoveAfterReturnDirection" value="0">
<param name="RightToLeft" value="0">
<param name="XMLURL" value="http://www.rgagnon.com/examples/xls/hello.xml">
</object>
<xparam name="HTMLURL" value="http://www.rgagnon.com/examples/xls/t1.html">
<xparam name="csvURL" value="http://www.rgagnon.com/examples/xls/t2.csv">

<script>
excel.range('a14').value = '435';
excel.range('b14').value = '0';
excel.range('c14').value = 'yop!';
excel.range('d14').value = 'yip!';
excel.range('e14').value = '';
</script>

<script>
function boldexcel(){
excel.ActiveCell.EntireRow.Font.Bold = true;
}
function excelalert(){
alert(excel.ActiveCell.Value);
}
function excelview(){
excel.ViewableRange="$A$1:$C$4";
}
</script>
<p>
<button onclick="boldexcel()">bold</button>
<button onclick="excelalert()">alert</button>
<button onclick="excelview()">view</button>