A must-have web development tool: Microsoft Fiddler

I've been using the slick little iehttpheaders tool to trace my browser's http traffic when troubleshooting issues. It logs out the requests, responses, cookies, HTTP headers etc... flowing back and forth. But the other day this MSDN article convinced me to spend a couple minutes looking at Fiddler, and I'm so glad I did. All I can say is Wow! This thing is going to come in handy. I wish I'd found it sooner.