Xander gave us a heads-up about a new Developer Toolbar for Internet Explorer. People have been using a similar toolbar in FireFox for developing webpages (which I never used, so can't say how nice it was).
Well, over the last week I've been using this developer toolbar and it's awesome!
Here's the MS link: http://www.microsoft.com/downloads/details.aspx?FamilyID=e59c3964-672d-4511-bb3e-2d5e1db91038&displaylang=en
Enjoy!