I had done some Outlook/Exchange programming back in the days of COM and OLE automation but never got a chance to do the similar kind of coding in .NET. I came across the following resources while searching on how to program against Outlook in Visual Studio. I am sure there are many other resources available but this is what I have so far.
What's New for Developers in Outlook 2007 (Part 1 of 2)
What's New for Developers in Outlook 2007 (Part 2 of 2)
Customizing the Ribbon in Outlook 2007
Creating an Outlook Task Add-in Solution with Visual Studio 2005 Tools for Office
Outlook 2007 Sample: Visual Studio 2005 Templates
Visual Studio 2005 Tools for Office Sample: Outlook Samples
Visual Studio 2005 Tools for Office Training: Outlook Hands-on Labs
Outlook 2007 Sample: Ribbon Extensibility Add-In
Visual Studio 2005 Tools for Office Sample: Outlook Tasks Add-in Sample
Outlook 2007 Add-Ins: RulesAddin, TravelAgencyAddin, and PrepareMeAddin
Outlook 2007 Sample: What's New Add-Ins
Outlook 2007 Add-In: Form Region Add-In
Outlook Add-in Snippets for Visual Studio 2005 Tools for Office
2007 Office System Sample: Visual Studio Code Snippets for the Office Fluent UI
Visual Studio 2005 Tools for Office Sample: Outlook Snippets
Office Developer Center
Outlook Developer Portal