O’Reilly recently published a book called Windows Developer Power Tools which contains tons of useful information about free tools you can use to work more efficiently, improve your Visual Studio experience and fill the gaps. I am glad to see that it included articles on popular add-ons to the Visual Studio Web development tools
CSS Properties Window add-on: http://safari.oreilly.com/0596527543/windowsdpt-CHP-8-SECT-8

ASP.NET/HTML Spell Checker add-on: http://safari.oreilly.com/0596527543/windowsdpt-CHP-8-SECT-5

Web Application Projects add-on: http://safari.oreilly.com/0596527543/windowsdpt-CHP-8-SECT-9

as well as a great set of articles on Web debugging tools.

Complete Table of Contents:  http://safari.oreilly.com/0596527543?tocview=true