Along the same lines, this is something similar going around today that re-uses the interface for the Webkit Web Inspector (which is a bit like Firebug).
Came across a very nifty utility for web developers – it’s called IETester.
It’s a web browser which allows you to open up different tabs for different versions of Internet Explorer all at the same time.
You can view IE 5, IE6, IE7 and IE8.
It seems to fall down with some complicated Javascript but it’s great for testing how a site renders in the different versions or as usual, sorting out IE6 problems!