Here is a very cool Windows Workflow Shell program. I'll have to find the session that Dharma is referring to here (where he uses the shell).

Makes use of the WorkflowCompiler class to build the workflow object on the fly from the XOML / XAML file. It even uses an anonymous delegate for the AssemblyResolve event that I recently discovered when looking at ASP.NET 2.0 resources. This event handler loads the workflow from the in-memory compiler results.

Very cool!!

He provides the source here
Less is More: Workflow Shell
(and if it's gone someday, my copy of it is here)