Firebug has been the developers dream when it comes to working on web development in Mozilla Firefox. In fact, it was such a great development tool, Microsoft attempted to copy the functionality of this tool to create their own IE Developer Toolbar, which now comes built in standard with IE8. For the most part they did a great job, and we now have a great development assistant for IE as with Firefox. However, the IE team missed a couple of things. Mainly, my grief is the lack of a console in the IE8 Toolbar, which allows me to see web service calls and duration length. You can see a general comparison between the toolbars in this outline:
Check out the link: http://getfirebug.com/firebuglite
Great addition, easy to use, no install!