During the last years I have written small, practical, articles with code samples about how to do things with Visual Studio add-ins like this:

HOWTO: Create a solution from a Visual Studio add-in
http://www.mztools.com/articles/2011/MZ2011001.aspx

And in the next years I hope to write lots of equivalent ones for Visual Studio packages, like this new one:

HOWTO: Create a solution from a Visual Studio package.
http://www.mztools.com/articles/2014/MZ2014013.aspx