Brian,
If you could send me the source, that would be great. That way I can cut and paste the content, like the code in the jsps and the classes.
Secondly, I am learning Struts 2, here. I think that my being a noobie is probably clear. So my recommendations may not be actually useful to the experienced user. But I will give it a try.
The Value stack is referenced by OGNL. So if you provide tools that could help construct OGNL epressions that reference stuff in the ValueStack or the ActionContext, that may be helpful. You probably already have tools that help look at the elements in the ValueStack or ActionContext, but if that is not the case, tools that help deconstruct the ValueStack and ActionContext would probably be useful too.
I hope that I am not giving you bad advice. I would hate to have you spend a lot of time implementing something that would have no value for the experienced user.
As I said, I am new to Struts 2, and Struts in general for that matter. If you give me 30 or 60 days, I should have my Struts 2 project implemented by then. Perhaps at that time, I can give you a more informed answer.