Would you like to view items stored in cache, and remove them for testing purposes? How about being able to view the page's view state (in various forms: raw, parsed, and decoded) to help you optimize your state management logic? Does ability to hide trace information from the page, and view it in a separate dialog, so it does not get in the way of your page's layout sound interesting?
All this and much more is available in this very cool tool -- Web Development Helper – available at http://www.nikhilk.net/project.webdevhelper.aspx.
If all you’re looking for is just a ViewState parser, there is also one at http://www.pluralsight.com/tools.aspx