GEO Source Code

Add-on for: IE Developer Toolbar
This add-on for Internet Explorer has the most features by-far of any that I have found. It has about as many features as the Web Developer toolbar for Firefox has. You are able to check elements and the source of the elements, it has a pixel ruler, you can outline divs/objects, highlighted source code viewer, you can disable css/javascript, a color picker to pick colors from any page and a lot more. I use this one quite a bit for numerous tasks in Internet Explorer.