Just found out from the IEBlog that Microsoft have released a beta of the IE Developer Toolbar.
It has some pretty nice features - you can view the HTML DOM of the current page, update attributes and styles of items on the page, toggle various useful pieces of info (such as image size, image path etc), and outline various types of element on the page. You can also do single click validation of the page etc.
Most web developers will probably find something useful in there. :-)
