Jester is a fairly unique testing tool for the Java language. It calls itself a "mutation testing" tool and aims to find code that might be marked as covered in a code coverage tool but that code might only be executed, not tested.
What Jester will do is introduce random changes to the code and re-run the tests -- if the tests still show green that means the code that was changed is either superfluous and can be deleted, or that you're not actually testing it. Both are great results to know.
What I'd like to see is the same thing for the English language. How much superfluous and useless language have you seen? (How much have you seen on this website? Wait, don't answer that...)
For instance, there's a sheet of paper in every meeting room at work with mostly commonsense guidelines. One of them has to do with food and drink, and it says: "Organization and cleanliness go a long way. Please be proactive in cleaning up after your meeting." What do you think Jester/English would do with that?