DebugBar is a plug-in for IE to help web developers and coders in development.
- DOM Inspector: View DOM Tree and modify tags attributes and css attributes on the fly to test your page
- HTTP Inspector: View HTTP/S request to check cookies, GET and POST parameters, view server info
- HTML Validator: Validate HTML code to correct and optimize your code and html size of your page
other features of this plugin include ablility to see page cookies, get pixel color on a page, make a page screenshot etc..
Debugbar is free for personal use, you need to buy a license for Professional use.