Developer Toolbar for IE

I came across this great tool for web developers, a little late since it was released
at the PDC.

With the IE Dev Toolbar you have several features at your fingertips to go deep
into existing pages or pages that you are currently creating. You will be able to
explore the DOM tree and find elements on the page, disable IE settings, view information,
outline elements, control images, resize pages to common screen resolutions and have
a powerful ruler that lets you measure pixel perfect content on your page. It also
will help you to validate against existing standards and provides pointers to W3C
specs.

Check out the IEBlog post and
then go download it.