Workflow Action List Window
I think it would be very useful to have a window in the designer that contained a list of all the workflow actions currently in use and allowed the user to click on an item and perhaps either jump to that action in the workflow (if possible) or at minimum open that action's configuration screen.
This way instead of looking at a giant workflow and trying to scroll through and over to try and find a given action, you would have a simple window to easily navigate through your actions.
Maybe you could even add some different sorting options to the list within the window, by say action type, alphabetical, etc...
Natalie Gimm commented
I would find that useful! Currently, you can use the "find in page" browser option to jump through the actions (eg. in IE it's Ctrl-F). I find it easier to see where it's jumped to if I zoom the browser out to the width of the workflow.