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)
http://www.mztools.com/resources_vsnet_addins.aspx#LearnVSXNow