FrontPage 2003 included several different ways to extend the FrontPage application, so if you're interested in extending FrontPage, you'll be interested in the article Getting Started Extending FrontPage 2003. This is a short article (3 pages) that discusses the different ways that you can extend FrontPage. Here's the summary:

Interested in extending FrontPage? Read this article to learn how you can extend Microsoft Office FrontPage 2003. FrontPage offers many techniques for you to broaden its functionality. This article reveals the different ways that you can extend FrontPage and provides pointers to detailed articles that walk you through each approach.