In MS Outlook it’s not possible to create native Add-ins as we can do in Excel. The only way is to create managed & unmanaged COM Add-ins. The first program that it was possible to create VSTO Add-ins for was Outlook. In my opinion these circumstances has lead to a situation where the group of professional Outlook developers has taken the lead when it comes to developing COM Add-ins.
One of the well known Outlook developers in the online community is Ken Slovak and his latest book Professional Outlook 2007 Programming (or at Wrox’s site) will soon be available. The projects and templates that are used in the book has the publisher (Wrox) agreed to make available for public download.
For some days ago I downloaded the VB.NET / VSTO 2005 SE projects and samples and spent time to evaluate them. Although we may not be interested to develop Add-ins for Outlook I find them to be great examples for creating robust and reliable managed COM Add-ins projects.
The projects and templates are available for download from Ken’s site:
Outlook 2007 Projects & Templates