I have recently completed to cover the ASP.NET Data Binding topic in my ASP.NET course. You can find its community version available for free personal usage at www.abelski.com. The following video clips were prepared in order to explain the basics of this topics. Both the source code shown in these clips and the slides can be found at www.abelski.com.
The Visitor Design Pattern
The visitor design pattern allows us to add operations to objects that already exist without modifying their classes and without extending them.