Internet Explorer Binary Behaviors in .NET

Wow, I didn't realize that you could create Internet Explorer binary behaviors with .NET. Behaviors are a feature introduced in Internet Explorer that allows you to attach new behaviors to existing tags or create new ones (i.e. I could create an ADDRESSBOOK tag and give it new behavior inside of HTML). Binary behaviors further extend this and allow you to write them in languages like C++, so you can do arbitrary 2D graphics for example or deeper extensions. It used to be that you had to know C++, but I just stumbled across a tutorial from 2003 where you could do it with .NET, which is much easier.