Spreadsheetml Websites
safe advertisement
SpreadsheetML - Articles, Templates and Add-Ins for Excel
SpreadsheetML.com - Your one stop source for information on SpreadsheetML and Add-Ins for Excel.
1,191,383 
$ 1,200.00
Eric White | Open XML
Blog on all-things Open XML, with a bit of Office / SharePoint thrown in
2,451,661 $ 480.00