This is an awesome little tool; "Web Development Helper is an Internet Explorer plugin that provides a set of useful tools to both Ajax/JavaScript developers as well as asp.net page and control developers."
You can download it here, for those who are unaware the guy who wrote it Nikhil Kothari is an architect on the asp.net team, he has a few projects you can see here. One (Script#) is a C# compiler that outputs JavaScript!! How cool is that!