For all those who didn’t try it, I strongly recommend to check out Internet Explorer Developer Toolbar.
This tool enables you to explore and troubleshoot web pages. You can explore and (what is more important) modify DOM. For example, you can find element by clicking on it, and then apply different CSS classes or styles. Or you can enable/disable elements and IE features, as well. You can also validate HYML and CSS. Useful feature is the one that enables you to get all information about elements. You can even selectively clear cache and cookies 
Click here to see the screenshot.
Download IE Dev Toolbar here.