If you are interested in the Windows Communication Foundation, then you really should follow Ralph Squillace's blog with keen interest. Ralph has the job of writing documentation for the technology, and his posts are packed with insightful riches.
This post is intended as a tribute to The Most Useful Windows Communication Foundation Blog Post Ever, which was Ralph's effort at showing how to use as many of the Windows Communication's extensibility points as possible. His post was based on the January CTP code, which is, notoriously, 90+ pages worth of breaking changes behind the February CTP version.
Go here to find a slide that provides a visual overview of most of the extensibility points, and code that shows you how to use them. The Word document included in the package steps you through the addition of each of the extensions.