Windows Live Writer Plugin API
Plugins are code libraries that add new functionality to Windows Live Writer. There are three basic types of plugins.
Publish Notification Hook Plugins execute code before and after Writer posts content to a blog. They can examine the contents of the post and have the option to cancel the publishing operation.
Content Source Plugins enable the user to insert new kinds of content into Writer.
Header/Footer Source Plugins automatically add content to the beginning or end of each blog post before it is published.