There are now eight books on Amazon that mention HttpWatch as a tool to aid HTTP debugging:

Professional ASP.NET 3.5: In C# and VB (Programmer to Programmer)
by Bill Evjen, Scott Hanselman, and Devin Rader

The Web Application Hacker’s Handbook: Discovering and Exploiting Security Flaws
by Dafydd Stuttard and Marcus Pinto

Juniper(r) Networks Secure Access SSL VPN Configuration Guide
by Rob Cameron and Neil R. Wyler

Practical JavaScript, DOM Scripting and Ajax Projects
by Frank Zammetti

Practical DWR 2 Projects (Expert’s Voice in Java)
by Frank Zammetti

SAP NetWeaver Visual Composer
by Carsten Býýnnen and Mario Herger

SAP® NetWeaver Portal Technology: The Complete Reference
by Rabi Jay

Advanced BSP Programming
by Brian McKellar and Thomas Jung