HTTP debugger/monitor

I came across Fiddler, a tool today that will be useful to anyone doing web development.

Firebug can do most of this too, however Fiddler is more browser-neutral and also allows the user to modify the incoming/outgoing data.
As a Firefox user, I use Firebug most of the time. Fiddler is a nice addition to my collection of tools.

Enjoy!

ps: Comments and/or links to this article are most welcome!