I'm not sure how I missed it, but the Internet Explorer Developer Toolbar version 1.00.2188.0 was released 5/7/2007. This is a free web page development tool by Microsoft. This is an add-on for Internet Explorer that enables the developer transverse and edit the page DOM, view object class names, match CSS selectors to page elements,  use a color picker and a pixel ruler. Other features include displaying image dimensions and table outlining.  

These tools are intended to help the developer diagnose and troubleshoot their web pages and doesn't including any script debugging at this time. I'll be adding this add-in a cool developer tool list that I have been working on.