The second session I delivered at the event was more lively than the first, and also much simpler. A level 300 session, but focused on beginner developers in .Net 3.0's WF.
There are two features of WF, which I was unfortunately unable to demonstrate at the session, which I really love: first, dynamic instance update - the ability to modify a running workflow in runtime, adding new activities and modifying its behavior. I can think of several uses for this, some on a professional level, some for fun. :-) The second is using custom activities together with WF to define Domain-Specific languages. Simpler than the DSL toolkit (and also with distinct applicabilities), and given the fact that you can run your declarative XAML workflows without recompilation, it's something I'm really looking into.