Note: This posting is for Beta 1 of Windows Workflow Foundation. For an updated Beta 2 build, please go to: http://blogs.msdn.com/markhsch/archive/2006/03/02/542596.aspx
Windows Presentation Foundation has XAMLPad as a tool. With this tool, you simply enter in some Xaml at the bottom and view the results within the application itself. Why not create something like that for Windows Workflow Foundation? So I did.
WFPad is the XAMLPad for Windows Workflow Foundation (as WF moves to XAML we'll see how XAMLPad works with this). You can use the designer and hit the down arrow for synchronization to instantly view the XOML for that workflow. On the flipside, you can enter in some XOML, hit the up arrow synchronization button and the designer will load that XOML and display the workflow accordingly. Being that it's an editor of sorts, you can save any workflow's to the file system as xoml files as well as load xoml files.
I also gave it the ability to navigate to an assembly containing workflow's, select a workflow within that assembly and then load it. I am able to extract the xoml just fine, but currently the designer is unable to load it (I know why, just not how to fix it yet).
This app only took about an hour to create (which is why I haven't figured out that bug) but would not have been possible without some additional legwork provided by other folks. I used the Workflow Designer Control and I am using the WorkflowAssembly class found in the WorkflowReflector project.
Let me know if you want me to add anything, but since I'm giving the source, it should be easy enough for you to expand.