The documentation is not strictly a tutorial, but it is still the best place to start. While my guide will cover the API, it won't cover all the details. However, it will make up for this by guiding the reader tyhrough the MPPlugin samples, and then moving onto useful tasks.
Addendedendedendumdum: I can write a number of VB samples, but my experience with C++ is lesser, and I would be grateful if people can send me/post here C++ code samples.
Addendedendedendumdum 2: Why can't I attach PDF files? O well, you can get it from my GeoCities site,
http://www.geocities.com/raceprouk/msn/plugins/guide_mp_plugins.pdf.
Addendedendedendumdum 3: I've now started adding code samples, starting with Registry access. I've replaced the version on the website as a result.