One problem when developing VBA applications is that bringing bugfixes and improvements to your users can be difficult since an Excel Workbook contains both, code and data. Certainly you cannot expect the typical MS Excel user to import .bas files or things like that.
To solve this problem, I wrote a small Excel tool called ‘VBA Updater’. It updates the VBA code of an Excel Workbook from another Workbook without touching the data in the Worksheets.
You can find a description and the tool at: VBA Updater