While very neat, I'm not sure entering these with text is the easiest approach. As soon as the automation fails to pick the right flow, you're basically stuck. A combination of text input and graphical manipulation might work better.
Lucidchart is awesome. Google would do well to make an acquisition there - I really feel the pain of not having any diagramming integrated with google docs.
For a nice graphical approach, I've found http://lucidchart.com to be excellent.