First of all, that title was a mouthful, so let me describe what I meant. A custom DataSource is something that you can assign (or databind) to the DataSource property of any bindable control. In programming terms, this means that the DataSource must implement IListSource, IDataSource, or IEnumerable. Well, I don't know about you, but I don't really want to spend a lot of time implementing all the methods of any of those interfaces. That's where Iterators come in; C# 2.0 added a new feature called Iterator blocks that makes it extremely easy to implement the IEnumerator interface, which is ...