Articles on developing Office COM add-in
in Visual Studio .net: VB.NET, C#, C++

Add-in Express™ Support Service
That's what is more important than anything else

Articles: Add-in Express for Office (.net and VCL)

Add-in Express 2010

General

Office COM add-in essentials

Office COM add-in GUI

Advanced Outlook regions

Outlook: insight studies

Excel, Word, PowerPoint