LearnVSXNow! (about Visual Studio packages), by Istvan Novak (DiveDeeper's blog)
MVP fellow Istvan Novak wrote long time ago a long series of small articles about Visual Studio Extensibility (VSX) with packages on his DiveDeeper's blog.
I have added a new section to my Resources about Visual Studio .NET extensibility page with sorted links to all of them:
LearnVSXNow!, by Istvan Novak (DiveDeeper's blog)